Pregnancy - ninshin (English spelling) pregnancy

Japanese: 妊娠 - にんしん（英語表記）pregnancy

Pregnancy is the phenomenon and state in which a fertilized egg makes a systematic connection with the mother and develops while transferring materials. In other words, it refers to the period from implantation to birth.

[Masao Arai]

Establishment of pregnancy

Pregnancy occurs through the following processes: (1) the formation and ovulation of female reproductive cells (eggs), (2) the formation and ejaculation of male reproductive cells (sperms), (3) fertilization, and (4) implantation of the fertilized egg.

[Masao Arai]

ovulation

This is the phenomenon in which a mature follicle in the ovary bursts and releases an egg. The ovulated egg is sucked into the fimbria of the fallopian tube by the suction action of the fimbria due to active oviduct movement and the ciliary movement of the fimbria. The life span of the egg is within 24 hours after ovulation, and if it passes beyond this time it loses its ability to be fertilized.

[Masao Arai]

ejaculation

When sexual excitement is heightened by sexual intercourse, ejaculation occurs, and sperm are released into the vagina along with semen. This semen contains hundreds of millions of sperm, which travel about 20 centimeters to the ampulla of the fallopian tube at a speed of about 2 to 3 millimeters per minute, taking anywhere from 2 to 3 hours to more than 10 hours to reach the ampulla. Sperm's fertilization capacity is said to last from 30 hours to 3 days in the uterus and fallopian tubes.

[Masao Arai]

Fertilization

If the sperm and egg meet in the ampulla of the fallopian tube, fertilization occurs. In many cases, the sperm reach the ampulla of the fallopian tube first and wait, but at least 60 sperm gather at the egg. Only one of them penetrates the egg and completes fertilization. The fertilized egg immediately begins cell division and begins to move into the uterus, but at this point the gender (male or female) has already been determined.

[Masao Arai]

Implantation

It takes 6 to 7 days for the fertilized egg to reach the uterine cavity, where it is embedded in the endometrium and forms a bond with the mother. This is called implantation, and it is thought to take 7 to 10 days from fertilization to implantation. After implantation, full development begins and the embryo becomes a fetus.

[Masao Arai]

Pregnancy

The true duration of pregnancy is from when the egg implants until birth (delivery), but the date of implantation is difficult to determine, so in clinical practice it is considered to be the period from the first day of the last menstrual period to delivery. In other words, from tens of thousands of cases in which the date of delivery was counted from the first day of the menstrual period (last menstrual period) before pregnancy, it was found that the average was approximately 280 days, and this is used as the expected delivery date. This number of 280 days is equivalent to 40 weeks, which makes 10 months if 4 weeks is considered one month of pregnancy, and since 4 weeks is 28 days and the number of days in the majority of menstrual periods, it was adopted as the pregnancy period for convenience. Therefore, only about 4% of women give birth on the expected date, and the majority give birth within a total of 4 weeks, 2 weeks before or after.

[Masao Arai]

Due date calculation method

To find out your due date, you can use a pregnancy calendar or similar table, but obstetricians and midwives use the following approximate method for estimating the due date. That is, the month of delivery is the number of months since the first day of your last menstrual period plus 9, and if the number is more than 12, subtract 3 from the number of months. The date of delivery is the number of months since the first day of your last menstrual period plus 7, and if it is more than 30, the number of months will increase by the number of months, and therefore the month of delivery will change to the following month. This method is not exact because it depends on the length of the month, but it can be used as a rough guide.

[Masao Arai]

Weeks of Pregnancy

The World Health Organization (WHO) expresses the length of pregnancy in full weeks, and the Japan Society of Obstetrics and Gynecology expresses it as the number of months and weeks of pregnancy to avoid confusion with the traditional method of calling months (counting months) based on 28 days per month in the pregnancy calendar. Births are also categorized by the number of weeks of pregnancy, with births up to 23 weeks called miscarriage, births between 24 and 36 weeks called premature births, births between 37 and 41 weeks called full-term births, and births after 42 weeks called postterm births.

[Masao Arai]

Pregnancy diagnosis

In most cases, it is not difficult to diagnose pregnancy. It is generally based on subjective symptoms and objective signs, although special diagnostic techniques are used for very early diagnosis.

[Masao Arai]

Signs of Pregnancy

There are two types of signs: suspicious signs, which are changes in the mother's body due to pregnancy, and definite signs, which are due to the presence of a fetus. Note that there are changes in the mother's body that appear outside the genitals, and changes that appear in the genitals; the former are sometimes called indeterminate signs. Indeterminate signs are signs of pregnancy, but are uncertain, and can appear due to other diseases in women other than pregnant women. That is, many of the subjective symptoms seen in early pregnancy include morning sickness, breast changes, frequent urination, and skin changes. In contrast, suspicious signs are objective signs that appear in the genitals but are also seen in conditions other than pregnancy. The main ones include amenorrhea, abdominal enlargement, changes in the shape of the uterus, lipid staining that turns the mucous membranes of the uterus and vagina purple, fetal movement, positive pregnancy test, and persistently high basal body temperature.

Definite signs that confirm the presence of a fetus are usually seen from the middle of pregnancy onwards. In recent years, fetal electrocardiograms and Doppler ultrasound have made it possible to detect the fetus at an earlier stage, but the traditional Traube stethoscope cannot detect fetal heart sounds until the 20th to 22nd week of pregnancy. Other definite signs include palpation of the fetal parts and confirmation of the fetal skeleton by X-ray (possible from the 18th to 20th week of pregnancy onwards).

[Masao Arai]

Early diagnosis

According to experienced doctors, more than 90% of diagnoses can be made by the second or third month of pregnancy based on various symptoms. However, it can be quite difficult in the very early stages. Clinically, it is also necessary to differentiate between abnormalities of pregnancy (ectopic pregnancy and hydatidiform mole) and whether the fetus is dead or alive. In recent years, these conditions, including those listed above, can be diagnosed with a fair degree of certainty through the use of endocrinology (hormones) and the application of ME (fetal electrocardiograms and ultrasound diagnosis).

Early diagnosis methods that utilize the dynamics of hormones that are important as pregnancy indicators are simple and often used. This method is to detect human chorionic gonadotropin in urine, which is secreted from chorionic tissue at the same time as implantation. In the past, biological pregnancy tests such as the Friedman reaction, the Aschheim-Zondec reaction, and the Meinini reaction, which were used to detect pregnancy using animals such as rabbits, mice, and frogs, were used, but due to time and effort, these tests are rarely used today, and immunological pregnancy diagnosis methods are used instead. This method makes use of the fact that human chorionic gonadotropin is a glycoprotein and has antigenicity, and involves injecting hormones purified from the urine of pregnant women into rabbits and other animals to collect serum containing antibodies, which is then used to examine and determine the antigen-antibody reaction. Currently, various immunological pregnancy diagnosis reagents are commercially available, and if the test is performed 24 days after fertilization, that is, when the expected menstrual period is more than about 10 days late, the result will be positive if pregnancy is detected.

There are also fetal electrocardiograms, which detect the active current of the fetal heart, and methods that apply continuous ultrasonic waves to the circulatory system to capture fetal blood flow signals using the Doppler effect, which are early diagnostic methods that can be used from around the sixth week of pregnancy.Currently, ultrasound tomography is often used, which can visualize the intrauterine gestational sac from the fifth week of pregnancy and visualize the fetus from the sixth week of pregnancy, as well as diagnose abnormalities such as multiple pregnancies, fetal death, and hydatidiform moles.

[Masao Arai]

Maternal changes

The maternal body undergoes remarkable changes, both functional and morphological, as the fetus develops rapidly during pregnancy.

[Masao Arai]

Genital changes

The most obvious change that occurs during pregnancy is the uterus, which grows larger, softens, and turns purple (lipid pigmentation), but the enlargement of the uterus is especially noticeable. In just 40 weeks, the uterus grows five times longer and 20 times heavier, occupying most of the abdominal cavity. That is, the uterus is the size of a goose egg at the end of the second month, the size of a fist at the end of the third month, the size of a newborn's head at the end of the fourth month, the size of a child's head at the end of the fifth month, and the fundus of the uterus reaches the navel at the end of the sixth month. The vagina also expands and lengthens significantly as pregnancy progresses, the vaginal walls become soft and moist, and lipid pigmentation is observed. Milky white vaginal discharge (leucorrhea) increases. The vulva also becomes soft and moist, and pigmentation increases. The breasts, which are called accessory sex organs, begin to grow from around the second month of pregnancy, and by the end of the pregnancy, they are three to four times their normal weight. The areola expands significantly and turns dark brown. After the fifth month, the baby will secrete colostrum if expressed, and it is not uncommon for accessory milk to appear.

[Masao Arai]

External changes

Pregnancy vomiting (morning sickness) begins around the sixth week of pregnancy, but subsides within two to three weeks. Pigmentation may appear on the face and abdominal wall, and stretch marks may appear on the abdomen. As the fetus develops, blood volume increases, putting more strain on the heart. The burden on the kidneys also increases, and pregnancy-induced diabetes and proteinuria may occur, and pressure on the bladder can lead to frequent urination. Weight can increase by 8 to 12 kilograms during pregnancy. Body temperature remains high during the luteal phase after ovulation, but tends to decrease as the pregnancy approaches the end.

[Masao Arai]

Menstruation and diet during pregnancy

Pregnancy is a physiological phenomenon, but neglecting your diet during pregnancy can become morbid and have a major impact on the mother and fetus. Pregnancy is divided into early, middle, and late stages based on the physiological progression of the mother and fetus, and each stage will be discussed below, focusing on physiology and diet.

[Masao Arai]

Early pregnancy

This refers to the first through fourth months of pregnancy. Many women go almost unaware of the first month, and by the time they become aware of their pregnancy due to the cessation of menstruation or morning sickness, it is already the second month. In the third month, the fetus begins to take on a more human form, and in the fourth month, the gender can be seen from the outside. The uterus becomes as large as the head at this time, and the placenta is fully formed. Morning sickness begins in the latter half of the second month and subsides in the latter half of the fourth month. The most important thing to be wary of throughout early pregnancy is miscarriage, and miscarriage is particularly likely in the second and third months, so couples should be cautious in their daily lives, avoid strenuous work and travel, get enough sleep, and be careful not to let their lower abdomen or lower back get cold.

[Masao Arai]

Mid-pregnancy

This refers to the fifth to seventh month of pregnancy. This is the most stable period, and the lower abdomen becomes more noticeable. It is also from this time that women start wearing abdominal bands. In the fifth month, the fetus's face becomes fully formed and the arms and legs begin to move. In other words, the mother's body can feel the fetus moving, and in primiparas this starts in the latter half of pregnancy, while in multiparas it starts in the first half. Appetite increases and the mood becomes more stable. Travel and dental treatments are done during this period, and should be discussed with a doctor. Preparations for childbirth, such as wearing maternity clothes, begin. In the sixth month, the lower abdomen gradually becomes larger and more noticeable, and in the seventh month, the breasts also become larger and colostrum is produced. Regular prenatal checkups, which were previously done every four weeks, are now done every two weeks. The fetus's skin also turns crimson and its face looks wrinkled like an old man's, and this type of birth is treated as premature birth.

[Masao Arai]

Late pregnancy

This refers to the 8th to 10th months of pregnancy. In the 8th month, the baby will often survive even if it is born. The femur (thigh) bone begins to ossify, so be careful of breech presentation. Have a pelvis measurement and blood test to be on the lookout for premature birth. The mother easily gets tired and feels pressure on the stomach. The lower limbs tend to swell. Take care to prevent pregnancy toxemia, limit fluid and salt intake, and occasionally elevate your legs to get plenty of rest. If you are returning to your parents' home to give birth, it is safer to do so by the end of the 8th month. In the 9th month, the fetus's skin will turn pink, hair will grow, and the genitals will be complete for both sexes. The mother will feel the fetus drop, and her chest will feel relaxed. To prevent premature birth and bacterial infection, avoid sexual intercourse and travel from the latter half of the month. Think about how to contact them in case of an emergency. In the 10th month, the fetus's skin will no longer wrinkle, there will be little downy hair, and it will be able to live a healthy life no matter when it is born, and preparations for childbirth will begin. As in early pregnancy, the mother's body begins to produce more urine and secretions. Biweekly check-ups are performed every week. Make sure you are properly prepared for birth and be on the lookout for premature rupture of the membranes.

[Masao Arai]

Prenatal checkups

Also known as prenatal health checkups, these are conducted to understand the physical and mental progress of pregnant women in order to ensure a normal pregnancy. They are necessary to detect and prevent pregnancy abnormalities such as preeclampsia and anemia early on, and as mentioned above, it is recommended that regular checkups be undertaken "once every four weeks until the seventh month of pregnancy, once every two weeks from the eighth to ninth month, and once a week from the tenth month until delivery." Under the provisions of the Maternal and Child Health Law, one checkup each in the early and late stages of pregnancy can be undertaken at public expense.

In addition, Article 15 of the Maternal and Child Health Law stipulates that pregnant women must promptly notify the mayor of their city, town or village, and once notification has been made to the city, ward or town office, they will be issued a Maternal and Child Health Handbook, a pregnancy health check-up ticket, information on mother's classes, etc. The pregnant woman is to fill out the notification form provided herself.

[Masao Arai]

Relationship between mother and fetus

During the short period of 10 months during which the fertilized egg develops into a complete fetus, the mother's body undergoes major changes in all areas, including metabolism and circulation. However, it should be considered that the reason she is still able to maintain a physiological state is because a dynamic equilibrium is maintained.

[Masao Arai]

Effects on the fetus

The health of the mother in the early stages of pregnancy has a particularly large impact on the fetus. Bleeding in the uterus can easily lead to nutritional and oxygen deficiencies in the fetus, and oxygen deficiency during the early stages of brain tissue formation can have a major impact. In addition, influenza, measles, chickenpox, rubella, and parotitis, which are caused by viruses, can easily cause miscarriage and can also cause disorders in the fetus. If symptoms such as high fever or a rash appear in the early stages, they should be reported to not only the internist but also the obstetrician. Toxoplasmosis, a parasitic disease found in dogs and cats, can also infect the human body. If infected during pregnancy, it can invade the fetus's brain and cause cerebral edema, cerebral palsy, epilepsy, and intellectual disability. Of sexually transmitted diseases, syphilis in particular can have a serious impact on the fetus, so blood tests should be performed during prenatal checkups, and if the test is positive, treatment should be started immediately. It is also not good to undergo X-rays and other tests that expose you to radiation more than necessary. Even progesterone hormones, used to prevent miscarriage, can cause damage to the fetus if used in large quantities in the early stages. In general, when using medicines such as antipyretics, tranquilizers, and hormones, you should always consult with a doctor and not take them recklessly and arbitrarily.

[Masao Arai]

Pregnant women and blood types

Although it is very rare, neonatal hemolytic jaundice caused by Rh blood type incompatibility can be a problem. Neonatal jaundice can also occur due to ABO blood type incompatibility. In either case, rapid advances in treatment have made it possible to cure many cases.

[Masao Arai]

Abnormalities during pregnancy

If you experience symptoms such as bleeding, severe abdominal pain, fever, swelling, dizziness, palpitations, headache, or blurred vision, see a doctor as soon as possible. In the early stages of pregnancy, bleeding may indicate miscarriage, ectopic pregnancy, or hydatidiform mole, while in the later stages, it may indicate premature birth or placental abruption. In most cases, time is of the essence, so even a small amount of bleeding should be diagnosed. In the case of severe abdominal pain, miscarriage or premature birth may be suspected, as well as cholelithiasis, appendicitis, gastric perforation, and ovarian cysts. Pre-labor pain is not very severe. Swelling may also cause pregnancy-induced toxemia or eclampsia. A high fever can easily induce miscarriage or premature birth, and can also affect the fetus. A severe headache may be caused by high blood pressure due to pregnancy-induced toxemia, or it may be a sign of eclampsia.

In addition, mild fever, headache, swelling, and back pain are common, and it is not good to become too nervous and lose mental stability.

[Masao Arai]

Abnormal pregnancy

These range from things that are of little concern to things that are dangerous, such as abnormalities in the number of fetuses, abnormalities in the implantation of the fertilized egg, and abnormalities in fetal development.

Multiple pregnancies are an abnormality in the number of fetuses and are not pathological, but they do require careful attention as they are prone to obstetric abnormalities. In recent years, their incidence has increased due to the widespread use of ovulation induction methods. Ectopic pregnancies are abnormalities in the implantation of a fertilized egg, and are most often tubal pregnancies, requiring open abdominal surgery. Placenta previa is also one type of implantation abnormality. Fetal growth retardation is another type of abnormality, and refers to low weight compared to gestational age, and is divided into fetal growth restriction and fetal nutritional disorders. A related disease is placental insufficiency syndrome. The babies are born premature or overmature.

Although unrelated to true pregnancy, phantom pregnancy is also a rare occurrence.

[Masao Arai]

Folklore

There are various ways to say "to conceive," "to be pregnant," and "to be pregnant" depending on the region. In Sannohe District, Aomori Prefecture, it is called Tanabu or Tanagu, in Shimane Prefecture, it is called Tanar, and in Futakawa Village, Maniwa District, Okayama Prefecture (now Maniwa City), it is called Gusui or Mimochi. In Suwa District, Nagano Prefecture, it is called Hinobe, and in Minami Shitara District, Aichi Prefecture, it is called Higatomaru, which means the cessation of menstruation. In Iki Island, Nagasaki Prefecture, conception is called Katal and pregnancy is called Haraum, which distinguishes it from the time when the fetus begins to grow. Although children are now thought of as something that we create ourselves, for a long time, Japanese people have not thought of conception as a mere physiological phenomenon, but have believed that "children are a gift from God." They have approached it with a pious awe and respect for God and nature, as something mysterious in which a new life and soul are contained within one's family. The proverb "A child is God's until seven" succinctly illustrates this idea. When a young bride finds out she is pregnant, the first person she usually tells is her mother back home. When the parents receive the news, they have a custom of greeting the mother-in-law of the in-laws with food, called tanominiiku. In Gifu, Fukui, Ishikawa and other prefectures, this is done around the second or third month of pregnancy, and the foods brought on this occasion include hagi mochi, udon noodles, red rice and mochi. In Yamato County, Fukuoka Prefecture, around the third or fourth month of pregnancy, people from the hometown would go to ask for tanominobatamochi, which they would then distribute to relatives and neighbors. If they received tanominobatamochi, they were expected to visit the mother-in-law after the birth. In Takayama Village, Agatsuma County, Gunma Prefecture, when a pregnancy is confirmed, the matchmaker gives a half-collar to the bride and tabi socks to the groom, and this is called Oeimochi no iwaiwai. When signs of pregnancy appear, some places hold pregnancy celebrations. Usually, this is for the first child, but in northwestern Yamanashi Prefecture, it is called Yujaku iwaiwai, and on Kikaijima Island in Kagoshima Prefecture, it is called Haramiburumai, and people from the countryside give gifts of rice cakes, fish, and other items to celebrate. In Uonome Village, Goto Island, Nagasaki Prefecture (now Shinkamigoto Town), when a woman becomes pregnant, relatives and close friends are invited to a banquet for the pregnant woman. This is called Neburumai, and the pregnant woman's home invites relatives and acquaintances in return. Morning sickness, a sign of pregnancy, is called kuse or kuseyami in the Tohoku region, but husbands can also experience a similar condition to morning sickness, and there is a proverb that says, "The only thing that can save you from illness is kuseyami." There are taboos regarding food and behavior during pregnancy, and these taboos overlap with prenatal education. Pregnant women are also believed to have magical powers, so they are often taken on board new ships to pray for a good catch.

[Yuki Ofuji]

The customs of various ethnic groups

How the physiological phenomenon of pregnancy is perceived and dealt with varies depending on society and culture.

Attitudes regarding sexual activity and gender roles in pregnancy are not uniform. Some societies do not consider pregnancy to be the result of sexual union. In the Trobriand Islands of Melanesia, pregnancy is the rebirth of the spirit of the dead entering the woman's womb. The reproductive power of the man's semen is not recognized, and sexual activity has no other meaning than, for example, making way for a child. The Australian indigenous Aranda also believe that conception occurs when the spirit of a totemic place enters a woman's body. Some societies have the opposite idea. For example, the Esse'eja of Bolivia believe that the entire body of a child is made from the father's semen, and the mother is merely a vessel. Therefore, the father must continue to provide semen so that the fetus can continue to grow after conception. Even if pregnancy is considered to be the result of sexual activity, societies often have different roles for the parents in the formation of the child. For example, the Kachin of Burma believe that the child's skeleton is made from the father's semen, but that the child receives flesh and blood from the mother, while the Ashanti of Africa believe that the child inherits blood (body) from the mother and the soul from the father.

During pregnancy, many taboos are imposed. Food taboos are especially prevalent. For example, among the Arapeshe of New Guinea, pregnant women are not allowed to eat pouches, which burrow deep into the ground and are said to cause difficult births. They also do not eat frogs or eels, as they cause premature births. The Desana of Colombia also have many prohibitions for pregnant women, many of which are food-related. For example, they cannot eat catfish, as in their symbolism they eat small fish that represent children. These food taboos are often imposed only on the woman, but they may also be imposed on her husband. Other behaviors are also forbidden. In Desana society, pregnant women are not allowed to touch hunting weapons or traps, and should not watch pottery being fired, as the pottery will break if she does. In many societies, pregnant women are believed to have extraordinary powers, but whether these powers are considered evil or good varies from society to society. The Desana people are the former, and an example of the latter is the Minangkabau people of Sumatra, who believe that pregnant women have the power to bring about a good rice harvest. Taboos during pregnancy are generally said to occur because breaking them can cause difficult childbirth or have a negative impact on the child. Actions that are associated with difficult childbirth, such as tying or fastening the vestments, are often forbidden. Sexual intercourse during pregnancy is also often prohibited. In the Trobriand Islands, sexual intercourse during pregnancy is strictly forbidden, as it is believed that the penis will kill the child. In many cases, the prohibition on sexual intercourse continues for several months after birth.

[Itabashi Masami]

Animal pregnancy

The state in which a fertilized mammalian egg attaches to the uterine wall, forms a placenta, supplies oxygen and nutrients to the mother, and excretes metabolic products, progressing through individual development. Generally, ovulated eggs are often fertilized in the oviduct. The fertilized egg divides as it descends from the oviduct to the uterus, becoming a hollow blastoid body called a blastocyst. When the blastocyst enters the uterine cavity and comes into contact with the uterine epithelium, some of the cells of the blastocyst become trophoblast cells, which phagocytize the uterine epithelial cells while invading the uterine matrix. The trophoblast cells gradually fuse and grow larger, penetrating deeper into the uterus and incorporating capillaries. This state is called implantation. Implantation requires luteinizing hormone and estrus hormone from the ovary, but once the placenta is formed, pregnancy is maintained by hormones derived from the placenta. The trophoblast cells that invade the uterus supply nutrients to the implanted embryo and eventually form the main part of the placenta. The placenta consists of the decidua derived from the uterine matrix, which is formed in response to implantation, and the chorion derived from the fetus. Chorionic epithelial cells release hormones such as luteinizing hormone and gonadotropic hormone into the mother. As pregnancy progresses, the fetus is surrounded by the chorion on the outside and the amnion on the inside, and is connected to the placenta by the umbilical cord. During this period, the decidua derived from the uterus thins, and only the maternal placenta remains beneath the developed fetal placenta. There are no particular structural changes to the uterus in subsequent pregnancies, and the fetus continues to develop.

Progesterone and estrus hormone are required for the formation of the decidua, which is necessary for implantation. These hormones may be secreted even if the blastocyst does not implant. When the cervix of a rat in estrus is repeatedly poked with a glass rod, the post-ovulatory follicle develops into a pregnant corpus luteum, which begins to secrete progesterone. At this point, mechanical or chemical stimulation of the uterus causes the decidua to form. This state is called pseudopregnancy. Endocrinologically, pseudopregnancy in rats is a state close to pregnancy, but in contrast to this, in humans, there is a luteal phase in the normal menstrual cycle during which progesterone is secreted, so physiologically this period can also be considered a short pseudopregnancy period.

Most viviparous animals are mammals, but in viviparous sharks, when the yolk of the fertilized egg is consumed, the yolk sac and the lower part of the oviduct combine to form a structure similar to the placenta, through which the shark larvae obtain nutrients from the mother and grow. This type of development inside the mother's body is also sometimes called pregnancy.

[Takasugi Akira]

"Vocabulary of Childbirth, Rearing and Customs" by Kunio Yanagita (1935, Imperial Gift Foundation Aiiku-kai) " ▽ "Compilation of Japanese Childbirth, Rearing and Customs" edited by the Imperial Gift Foundation Maternal and Child Aiiku-kai (1968, Daiichi Hoki Publishing)" ▽ "Infant Raising" by Yuki Ofuji (1968, Iwasaki Bijutsu-sha)

Pregnancy and changes in the fertilized egg, fetus, and mother
©Shogakukan ">

Pregnancy and changes in the fertilized egg, fetus, and mother

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

妊娠とは、受精卵が母体と組織的連絡を生じ、物質の授受を行いながら発育していく現象およびその状態をいう。つまり着床から出産までの期間をさすわけである。

［新井正夫］

妊娠の成立

妊娠は(1)女性生殖細胞である卵の形成と排卵、(2)男性生殖細胞である精子の形成と射精、(3)受精、(4)受精卵の着床、以上の過程を経て成立する。

［新井正夫］

排卵

卵巣内で成熟した卵胞が破裂して卵を排出する現象で、排卵した卵は活発な卵管の運動による卵管采(さい)部の吸引作用と卵管采の繊毛運動によって卵管采内に吸い込まれる。卵の寿命は排卵後24時間以内であり、それ以上経過すると受精能力を失う。

［新井正夫］

射精

性交によって性的興奮が高まると射精がおこり、精液とともに精子が腟(ちつ)内に射出される。この精液内には数億の精子が含まれており、1分間に約2～3ミリメートルの速度で卵管膨大部までの約20センチメートルの距離を進み、2～3時間から十数時間かかって到着する。精子の受精能力は子宮や卵管内で30時間から3日以内といわれる。

［新井正夫］

受精

卵管膨大部で精子と卵が都合よく巡り会えば受精がおこる。多くの場合、精子が先に卵管膨大部に達して待機するが、少なくとも60個以上の精子が卵に集まる。そのうち1個だけが卵に侵入して受精を完了することになる。受精卵はただちに細胞分裂を開始し、子宮内へ移動を始めるが、このとき男女の性別はすでに決定している。

［新井正夫］

着床

受精卵は6～7日かかって子宮腔(くう)内に到達し、子宮内膜に埋まって母体と関係をもつようになる。これが着床で、受精から着床までは7～10日間とみられている。着床後は本格的な発育が始まり、胎児となる。

［新井正夫］

妊娠期間

真の妊娠持続期間は卵が着床したときから出産（分娩(ぶんべん)）までであるが、着床の日はわかりにくく、臨床上は最終月経の第1日から分娩に至るまでの期間としている。すなわち、妊娠する前の月経（最終月経）の第1日から数えて分娩が何日目にあるかを調べた何万という例から、その平均がだいたい第280日目であることがわかり、これを出産予定日としている。この280日という数は40週に相当し、4週間を妊娠の1か月と考えれば、10か月になるわけで、しかも4週間は28日間で大多数の月経期間の日数とも一致するところから、便宜上、妊娠期間として採用されたわけである。したがって、予定日に出産するのは4％くらいで、大多数はその前後2週間ずつ、計4週間のうちに出産する。

［新井正夫］

出産予定日算出法

出産予定日を知るには一覧表になった妊娠暦などを利用すればよいが、産科医や助産師は次のような予定日概算法で計算している。すなわち、最終月経の開始日の月数に9を加えた数が出産月で、12より多くなるときは月数から3を引く。出産日は最終月経の開始日の数に7を加えた数で、30より多くなれば多くなった数だけ翌月に回り、したがって出産月が翌月に変わる。月の大小などがあるので正確とはいえないが、だいたいの目安にはなる。

［新井正夫］

妊娠週数

WHO（世界保健機関）では満の妊娠週数で妊娠期間を表現することになっており、日本産科婦人科学会では、従来の妊娠暦による28日を1か月とした月数（数え月）の呼び方との混乱を避けるため、妊娠第何か月、第何週と表現することにしている。なお、出産についてもこの妊娠週数で区別し、妊娠23週までの分娩を流産、妊娠24～36週を早産、妊娠37～41週を正期産、妊娠42週以降を過期産とよんでいる。

［新井正夫］

妊娠の診断

多くの場合、妊娠の診断を下すことは困難ではない。一般的には自覚的な症状と他覚的な徴候に基づいて行われるが、ごく早期の診断には特別な診断法を用いる。

［新井正夫］

妊娠の徴候

妊娠による母体の変化としてみられる疑徴と、胎児の存在による確徴とに分けられる。なお、母体の変化には性器以外に現れる変化と、性器に現れる変化とがあり、前者を不確徴といって区別することもある。不確徴は妊娠の兆しではあるが不確かなもので、妊婦以外にも他の疾患のために現れることがある。すなわち、つわり、乳房の変化、頻尿、皮膚の変化など、妊娠早期にみられる自覚的症状が多い。これに対して性器に現れる変化であるが、妊娠以外の状態でもみられる他覚的徴候が疑徴である。おもなものをあげると、無月経、腹部の膨大、子宮の形状変化、子宮や腟の粘膜が紫色に変色するリピド着色、胎動感、妊娠反応陽性、基礎体温の高温持続などがある。

　胎児の存在が確認できる確徴は普通、妊娠中期以後にみられる。近年は胎児心電図や超音波ドップラー法によってかなり早期に検出可能となったが、従来のトラウベ聴診器による胎児心音の聴取は妊娠20～22週にならないと聴取できない。また、胎児部分の触知やX線写真による胎児骨格の証明（妊娠18～20週以後に可能）なども確徴の一つである。

［新井正夫］

早期診断法

熟練した医師によれば、妊娠2～3か月ごろにはいろいろな徴候によって90％以上は診断がつく。しかし、ごく早期にはかなり困難なことがある。また、臨床的には妊娠の異常（子宮外妊娠や胞状奇胎）、胎児の生死などの鑑別も必要となる。これらを含めて近年は、内分泌学（ホルモン）の利用やMEの応用（胎児心電図や超音波診断）によって相当確実に診断されるようになった。

　妊娠反応として重要なホルモンの動態を利用した早期診断法が簡単でよく用いられる。これは、着床と同時に絨毛(じゅうもう)組織から分泌されるヒト絨毛性ゴナドトロピンを尿中に証明する方法で、かつてはウサギ、ネズミ、カエルなどの動物を用いて検出するフリードマン反応、アシュハイム‐ツォンデック反応、マイニーニ反応など生物学的妊娠反応を利用していたが、時間や手間の関係で現在はほとんど行われず、もっぱら免疫学的妊娠診断法が行われている。これは、ヒト絨毛性ゴナドトロピンが糖タンパクで抗原性をもっているのを利用し、妊婦尿から精製したホルモンをウサギなどに注射して抗体を含む血清を採取し、これを用いて抗原抗体反応を調べて判定する方法である。現在、いろいろな免疫学的妊娠診断試薬が市販されているが、受精後24日、すなわち予定月経が約10日以上遅れている場合に調べると、妊娠ならば陽性となる。

　また、胎児の心臓の活動電流を検出する胎児心電図や循環器に超音波の連続波を与えておこるドップラー効果を応用して胎児の血流信号をキャッチする方法もあり、妊娠六週ころから可能な早期診断法である。現在では超音波断層法を利用することが多くなり、妊娠五週から子宮内胎嚢(たいのう)を描出、妊娠六週からは胎児像が描出できるほか、多胎妊娠、胎児死亡、胞状奇胎などの異常診断も可能である。

［新井正夫］

母体の変化

妊娠の徴候の一つとしてみられる母体の変化は、胎児の急速な発育とともに機能的にも、形態的にも著しくなる。

［新井正夫］

性器の変化

妊娠に伴う変化のうちもっとも顕著なものが子宮で、大きさが増し、軟化し、紫色に着色する（リピド着色）が、とくに目だつのが子宮の増大である。わずか40週の間に子宮の長さで約5倍、重さで約20倍となり、腹腔の大部分を占めるようになる。すなわち、子宮は第2か月末でガチョウの卵大、第3か月末で手のこぶし大、第4か月末で新生児頭大、第5か月末で小児頭大となり、第6か月末で子宮底の高さがへそに達する。また、腟も妊娠の進行とともに著しく拡大延長し、腟壁は潤軟となり、リピド着色がみられる。乳白色のおりもの（帯下(たいげ)）が増加する。外陰部も潤軟となって色素の沈着が増加する。副性器といわれる乳房は妊娠第2か月ころから増大し、末期には普段の3～4倍の重さとなる。乳輪は著しく拡大して暗褐色に着色する。第5か月を過ぎると、圧出すれば初乳を分泌する。副乳がみられることも珍しくない。

［新井正夫］

性器外の変化

妊娠第六週ころから妊娠嘔吐(おうと)（つわり）が始まるが、2～3週間で軽快する。顔面や腹壁などに色素沈着が現れたり、腹部に妊娠線が現れたりする。また、胎児の発育に伴って血液量が増加し、心臓の負担が増大する。腎臓(じんぞう)の負担も増大して妊娠性の糖尿やタンパク尿がみられることがあり、膀胱(ぼうこう)が圧迫されて頻尿になりやすい。体重は妊娠中に8～12キログラムの増加がみられる。体温は排卵後の黄体期高温相が持続するが、末期に近づくにつれて下降傾向がみられる。

［新井正夫］

妊娠中の生理と摂生

妊娠は生理的現象であるが妊娠中の摂生を怠ると病的になり、母体および胎児にも大きい影響を与える。妊娠期間は母体や胎児の生理的経過などから初期、中期、後期に分けられるが、以下それぞれについて生理と摂生を中心に述べる。

［新井正夫］

妊娠初期

妊娠第1か月から第4か月までをいう。第1か月はほとんど気づかずに過ごしてしまう場合が多く、月経閉止やつわりなどで妊娠に気づくころは第2か月になっている。第3か月になると胎児も人間らしい形態になり、第4か月では性別が外見上わかるようになる。子宮はこのころに児頭大となり、胎盤も完成する。つわりは第2か月後半から始まり、第4か月の後半には軽快する。妊娠初期を通じてもっとも警戒すべきものは流産であり、とくに第2、第3か月は流産しやすいので、夫婦生活も慎重にし、激しい仕事や旅行を避け、睡眠を十分にとり、下腹部や腰部が冷えないように注意する。

［新井正夫］

妊娠中期

妊娠第5か月から第7か月までをいう。もっとも安定した期間で、下腹部も目だってくる。腹帯の着用を開始するのもこの時期からである。第5か月になると胎児の顔も整い、手足の運動が始まる。すなわち、母体は胎動を感ずるわけで、初産婦では後半から、経産婦では前半から感ずるようになる。食欲が出て気持ちも落ち着いてくる。旅行や歯の治療などは医師に相談して、この時期に行う。妊婦服（マタニティ・ドレス）などの出産準備を始める。第6か月になると下腹部がだんだん大きくなって目だつようになり、第7か月では乳房も大きくなって初乳が出たりする。四週ごとだった妊婦定期検診も二週ごとに受ける。胎児の皮膚も深紅色になり、顔つきは老人のようにしわだらけで、出産の種類としては早産として扱われる。

［新井正夫］

妊娠後期

妊娠第8か月から第10か月までをいう。第8か月になると生まれても助かる場合が多くなる。大腿(だいたい)骨の化骨が始まり、骨盤位（さかご）に注意する。骨盤計測や血液検査などを受け、早産を警戒する。母体は疲れやすく、胃が押される感じがする。下肢がむくみやすくなる。妊娠中毒症の予防を心がけ、水分や塩分の摂取を控え目にし、ときどき足を高くして十分に休養をとる。実家へ帰って分娩する場合は、第8か月の末ごろまでに帰ったほうが安全である。第9か月になると胎児の皮膚はバラ色になり、頭髪も生えて男女とも性器が完成する。母体は胎児が下がった感じで、胸が楽になる。早産および細菌感染の予防上、後半からは夫婦生活や旅行を避ける。万一の場合の連絡方法なども考えておく。第10か月になると胎児の皮膚にしわがなくなり、うぶ毛も少なく、いつ出産しても元気に生活できるようになっており、出産の準備が始まる。妊娠初期と同様に、母体では尿が近くなり分泌物が増えてくる。二週ごとの検診は毎週行われる。出産準備に手落ちのないよう確かめ、早期破水を警戒する。

［新井正夫］

妊婦検診

妊婦健康診査ともいい、正常な妊娠経過を図るために妊婦の心身の経過を把握することを目的として行われる。妊娠中毒症や貧血など妊娠の異常を早期に発見し予防するために必要であり、定期検診は前述のように「妊娠第7か月までは4週間に1回、第8～9か月は2週間に1回、第10か月から分娩までは1週間に1回」受けることが望ましい。母子保健法の規定によって妊娠前期と後期各1回は公費で受けられる。

　なお、母子保健法第15条によって、妊娠した者は市町村長に速やかに妊娠の届出をするよう定められており、市区役所または町村役場に届出を済ませると母子健康手帳、妊婦健康診査受診票、母親学級の案内などが交付される。届出は妊婦自身が備え付けの用紙に記入して行うことになっている。

［新井正夫］

母体と胎児との関係

10か月という短期間に受精卵が完全な胎児にまで発育する間、母体もこれに伴って代謝や循環などあらゆる面で大きな変動がみられるが、なお生理的状態を保ちうるのは動的平衡関係が維持されているためと考えるべきであろう。

［新井正夫］

胎児への影響

妊娠初期の母体の健康は胎児への影響がとくに大きい。子宮内の出血は胎児の栄養不足や酸素不足を招きやすく、脳組織ができ始める初期における酸素不足は大きな影響を与える。また、ウイルスによる流感、麻疹(ましん)、水痘、風疹、耳下腺(せん)炎などは流産をおこしやすく、胎児に障害が生ずる場合もある。初期に高熱や発疹(ほっしん)などの症状が現れたときは、内科医ばかりでなく産科医にも報告する。イヌやネコなどの寄生虫症であるトキソプラズマ症も、人体に感染することがあり、妊娠中に感染すると胎児の脳に侵入して脳水腫(すいしゅ)、脳性麻痺(まひ)、てんかん、知的障害の原因となる。性病のうち、とくに梅毒は胎児に深刻な影響を与えるので、妊婦検診で血液検査を行い、陽性の場合はただちに治療を始める。また、必要以上にX線検査などを行い放射線の照射を受けるのもよくない。流産防止用の黄体ホルモンも、初期に大量使用すると胎児に障害が生ずる場合がある。一般に解熱剤、精神安定剤、ホルモン剤など、薬剤を使用する場合はかならず医師に相談し、独断で軽率な服用をしてはならない。

［新井正夫］

妊婦と血液型

頻度は非常に少ないが、Rh式血液型不適合妊娠による新生児溶血性黄疸(おうだん)が問題になる。また、ABO式血液型不適合でも新生児黄疸がみられる。いずれにしても、治療対策の急速な進歩によって多くのものは治癒されるようになった。

［新井正夫］

妊娠中の異常

出血、激しい腹痛、発熱、むくみ、めまい、動悸(どうき)、頭痛、視力減退などの症状が現れた場合は、早めに医師の診断を受ける。出血の場合は、妊娠初期では流産、子宮外妊娠、胞状奇胎などのおそれがあり、後期では早産、胎盤早期剥離(はくり)などの疑いがある。いずれも一刻を争う場合が多く、少量の出血でもいちおうの診断を受けておく。激しい腹痛の場合は流・早産の疑いのほか、胆石症、虫垂炎、胃穿孔(せんこう)、卵巣嚢腫(のうしゅ)などのおそれもある。前駆陣痛の場合の痛みは、あまりひどくない。むくみの出る場合は、妊娠中毒症や子癇(しかん)の原因にもなる。高熱の場合は流・早産を誘発しやすく、胎児にも影響がある。激しい頭痛は妊娠中毒症による高血圧が原因の場合もあり、子癇の前兆の場合もある。

　なお、軽い発熱、頭痛、むくみ、腰痛などはよくみられるもので、あまり神経質になりすぎて精神の安定を欠くのもよくない。

［新井正夫］

異常妊娠

胎児の数の異常、受精卵の着床の異常、胎児の発育の異常など、あまり心配のいらないものから危険なものまである。

　多胎妊娠は胎児の数の異常で、病的なものではないが、産科的な異常がおこりやすいので十分に注意する必要がある。近年は排卵誘発法の普及によって増えている。子宮外妊娠は受精卵の着床の異常で、卵管妊娠の場合がもっとも多く、開腹手術を行う。なお、前置胎盤も着床異常の一つである。また、胎児の発育の異常としては子宮内発育遅延があり、在胎週数に比し体重の少ないものをいい、胎児発育不全と胎児栄養障害に分けられる。これと関連する疾患に胎盤機能不全症候群がある。出生時には未熟児や過熟児となる。

　なお、真の妊娠とは無関係であるが、想像妊娠もまれにみられる。

［新井正夫］

民俗

受胎すること、はらむ、身ごもることで、地方によっていろいろな言い方がある。青森県三戸(さんのへ)郡ではタナブとかタナグ、島根県ではタナル、岡山県真庭郡二川村（現、真庭市）ではグスイとかミモチという。長野県諏訪(すわ)地方でヒノベ、愛知県南設楽(みなみしたら)郡でヒガトマルというのは、月経の停止を意味している。長崎県壱岐(いき)島では、受胎することをカタル、妊娠することをハラウムといって、胎児が成長し始めてからのことと区別している。いまでは子供は自分たちでつくるものと考えられているけれども、日本人は長い間、身ごもるということを単なる生理現象とは考えずに、「子供は神からの授かりもの」と信じてきた。新たな命、魂が身内にこもるという神秘的なものとして、神と自然に対して敬虔(けいけん)な畏(おそ)れと謹みの心で対してきた。「七つまでは神の子」ということわざは、端的にこの考え方を示している。妊娠したことがわかって若い嫁が最初に打ち明けるのは、普通、里の母親である。知らせを受けると里の親はタノミニイクといって、食物などをもって婚家の姑(しゅうと)へ挨拶(あいさつ)する風習がある。岐阜、福井、石川県などでは2、3か月目くらいに行うが、このとき持って行く食物は、萩(はぎ)の餅(もち)、うどん、赤飯、餅などであった。福岡県山門(やまと)郡では、妊娠3、4か月ごろ、里方からタノミノボタモチを持って頼みに行き、これを親戚(しんせき)・近所へも配る。タノミノボタモチをもらえば、出産後、産見舞に行くべきものであった。群馬県吾妻(あがつま)郡高山村では、妊娠が決まると、仲人(なこうど)が嫁方へ半衿(はんえり)、婿(むこ)方へ足袋(たび)などを贈り、これをオエイモチの祝いといった。妊娠の兆候が現れると、妊娠祝いをする所がある。普通初子の場合であるが、山梨県北西部ではユウジャク祝い、鹿児島県喜界島(きかいじま)ではハラミブルマイといって、里方から餅、魚などを贈って祝う。長崎県五島の魚目村（現、新上五島(しんかみごとう)町）では、妊娠すると親類や懇意な者が妊婦を招いて饗応(きょうおう)する。これをネブルマイといい、妊婦の家では返礼に親戚・知人を招く。妊娠のしるしとしてのつわりを、東北地方ではクセとかクセヤミというが、夫がつわりと同様な状態になることがあり、「病んで助(す)けられるのはクセヤミばかり」ということわざがある。妊娠中は食物や行動についての禁忌があり、禁忌は胎教とも重なっている。また、妊婦は呪力(じゅりょく)をもつものとして、新造船に乗せて豊漁を願うことなどが行われた。

［大藤ゆき］

諸民族の習俗

妊娠という生理的現象をどのようにとらえ、どのように対処するかは社会、文化によって異なる。

　妊娠に対する性行為と男女の役割に関する観念は一様ではない。妊娠を性的結合の結果と考えない社会もある。メラネシアのトロブリアンド諸島では、妊娠は死者の霊が女性の胎内に入って再生することだという。男性の精液が生殖力をもつことは認識されず、性行為もたとえば子供の通り道をあけるといったこと以上の意味はもたない。オーストラリア先住民のアランダ人もトーテム聖地の精霊が女性の体に入ると受胎すると考える。これとは逆に考える社会もある。たとえばボリビアのエセエハ人は、子供の体はすべて父親の精液によってつくられ、母親は単に容器でしかないという。そのため妊娠後も胎児が成長し続けるために父親は精液を供給し続けなければならないと考える。妊娠を性行為の結果とみなしても、子供の形成に果たす両親の役割が異なる社会もしばしばある。たとえばビルマのカチン人では、子供の骨格は父親の精液でつくられるが、肉と血は母親からもらうと考え、アフリカのアシャンティ人は、血（肉体）を母親から、魂を父親から受け継ぐと信じている。

　妊娠中はたいてい種々の禁忌が課せられる。とくに広くみられるものは食物の禁忌である。たとえばニューギニアのアラペシュ人では妊婦はフクロネズミを食べてはいけない。フクロネズミは地面に深く潜るのでこれを食べると難産になるという。カエルとウナギは早産になるので食べない。コロンビアのデサナ人も妊婦は多くの禁止に従わなければならないが、その多くは食物に関係している。たとえばナマズは彼らのシンボリズムでは、子供を意味する小魚を食べるので、食べてはいけない。このような食物禁忌は女性だけに課せられることが多いが、夫にも禁止される場合もある。そのほか種々の行動が禁止される。デサナの社会では妊婦は狩猟の武器や罠(わな)に触れてはいけない。土器を焼いているところを妊婦が見ると土器は割れてしまうので見てはいけない。このように妊婦が異常な力をもっていると考えられる社会は多いが、その力を悪と考えるか善とみなすかは社会によって違う。デサナ人は前者であり、後者の例としては、たとえばスマトラのミナンカバウ人では妊婦は稲の豊作をもたらす力をもっているとされる。妊娠中の禁忌は一般にそれを犯すと難産になったり子供に悪い影響を与えるからといわれる。結んだり、閉めたりといった難産を連想させる行動がよく禁止される。妊娠中の性行為も多くの場合禁止される。トロブリアンド諸島では妊娠中に性交すると男根が子供を殺してしまうとして厳しく禁じられる。性交の禁止が出産後数か月続く場合も多い。

［板橋作美］

動物の妊娠

哺乳(ほにゅう)類の受精卵が子宮壁に定着し、胎盤を形成して母体との間に酸素や栄養の供給と代謝産物の排出を行って、個体発生を進行させている状態をいう。一般に排卵した卵は輸卵管内で受精することが多い。受精した卵は輸卵管から子宮に向かって下降している間に分裂して、胚盤(はいばん)胞とよばれる中空の胞状体となる。胚盤胞が子宮腔(こう)に入り子宮上皮と接触すると、胚盤胞の細胞の一部が栄養芽細胞となって、子宮上皮細胞を貪食(どんしょく)しつつ子宮基質へと侵入する。栄養芽細胞はしだいに癒合して巨大化し、子宮内に深く侵入して毛細血管を取り込むようになる。この状態を着床という。着床には卵巣の黄体ホルモンや発情ホルモンが必要であるが、胎盤が形成されると胎盤由来のホルモンによって妊娠が維持される。子宮に侵入した栄養芽細胞は着床した胚に栄養を供給し、やがて胎盤の主要部分を形成する。胎盤は、着床に反応して形成された子宮基質由来の脱落膜と、胎児由来の絨毛(じゅうもう)膜とからなる。絨毛上皮細胞からは黄体ホルモンや生殖腺(せん)刺激ホルモンなどが母体に放出される。妊娠が進むにしたがって、胎児は外側が漿膜(しょうまく)に、内側が羊膜に包まれ、胎盤とは臍帯(せいたい)で連絡する。この時期には子宮由来の脱落膜は薄くなり、発達した胎児性胎盤の下に母性胎盤として残るだけとなる。これ以後の妊娠にはとくに子宮の構造上の変化はなく、胎児の発達が進行する。

　着床に必要な脱落膜形成には黄体ホルモンと発情ホルモンが必要である。これらのホルモンは、胚盤胞が着床しなくとも分泌されることがある。発情期のラットの子宮頸管(けいかん)部をガラス棒で繰り返し突くと、排卵後の濾胞(ろほう)が妊娠黄体にまで発達し、黄体ホルモンを分泌するようになる。このとき、子宮を機械的、化学的に刺激すると脱落膜が形成される。このような状態を偽(ぎ)妊娠という。ラットの偽妊娠は内分泌的には妊娠に近い状態であるが、これに対しヒトの場合には、通常の月経周期にも黄体ホルモンの分泌される黄体期があるから、この期間は生理学的には短い偽妊娠期ともいえよう。

　なお、胎生動物の大部分は哺乳動物であるが、胎生のサメ類では受精卵の卵黄が消費されると卵黄嚢と輸卵管下部とが結合して胎盤に類似した構造となり、ここを通してサメの幼生は母体から栄養をとり成長する。このような母体内発育も妊娠ということがある。

［高杉　暹］

『柳田国男著『産育習俗語彙』（1935・恩賜財団愛育会）』▽『恩賜財団母子愛育会編『日本産育習俗資料集成』（1968・第一法規出版）』▽『大藤ゆき著『児やらい』（1968・岩崎美術社）』

[参照項目] | 血液型不適合妊娠 | 交換輸血 | 射精 | 受精 | 出産 | 人工授精 | 新生児黄疸 | 想像妊娠 | 胎児 | 排卵 | 副乳 | 母子保健

妊娠期間と受精卵、胎児、母体の変化

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例

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Establishment of pregnancy

ovulation

ejaculation

Fertilization

Implantation

Pregnancy

Due date calculation method

Weeks of Pregnancy

Pregnancy diagnosis

Signs of Pregnancy

Early diagnosis

Maternal changes

Genital changes

External changes

Menstruation and diet during pregnancy

Early pregnancy

Mid-pregnancy

Late pregnancy

Prenatal checkups

Relationship between mother and fetus

Effects on the fetus

Pregnant women and blood types

Abnormalities during pregnancy

Abnormal pregnancy

Folklore

The customs of various ethnic groups

Animal pregnancy

妊娠の成立

排卵

射精

受精

着床

妊娠期間

出産予定日算出法

妊娠週数

妊娠の診断

妊娠の徴候

早期診断法

母体の変化

性器の変化

性器外の変化

妊娠中の生理と摂生

妊娠初期

妊娠中期

妊娠後期

妊婦検診

母体と胎児との関係

胎児への影響

妊婦と血液型

妊娠中の異常

異常妊娠

民俗

諸民族の習俗

動物の妊娠

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