Birth - Shussan (English spelling) Parturition

Japanese: 出産 - しゅっさん（英語表記）parturition

Childbirth is the act of giving birth, and medically it refers to the phenomenon in which the fetus and its appendages (umbilical cord, placenta, membranes, amniotic fluid) that have been developing for a certain period of time inside the pregnant mother's uterus are expelled to the outside world by the force of labor pains and abdominal pressure. A woman in labor is a parturient woman, and a first-time birth is called a primipara, while a woman who has already given birth is called a multipara. A primipara under the age of 19 is called a young primipara, a primipara over the age of 35 is called an elderly primipara, and a woman who has given birth five or more times is called a multipara. The World Health Organization (WHO) defines a primipara over the age of 35 as an elderly primipara.

[Masao Arai]

Classification

There are various types of childbirth. In terms of classification based on gestational age, births between 37 and 41 weeks are full-term births, births before 36 weeks are premature births, and births after 42 weeks are postterm births. Premature births are further classified as premature births in the strict sense, and births before 24 weeks are miscarriages. In terms of the process of childbirth, a normal birth is one in which the process goes smoothly and both the mother and child are healthy, while an abnormal birth is one in which the process is abnormal and puts the mother and child at risk. Generally, the three main elements of childbirth are the birth canal, which consists of the bone and soft birth canals, the expulsive force, which consists of labor pains and abdominal pressure, and the fetus and its appendages. If there is an abnormality in any of these, the progress of childbirth is hindered, resulting in abnormal childbirth. Based on whether artificial assistance is used, childbirth is classified as natural or artificial. Also, depending on the number of fetuses, births are called single births when there is one, and multiple births when there are two or more fetuses, and multiple births are also called twin births, triplets births, etc. Depending on the survival of the newborn, births are also divided into live births and stillbirths.

In addition, commonly known as an easy birth, it refers to a normal, natural birth, while an abnormal birth is called a difficult birth. Here, we will focus on normal birth.

[Masao Arai]

Birth progress

Labor begins with regular uterine contractions, or labor pains (approximately every 10 minutes), and ends with the opening of the closed cervix, followed by the expulsion of the fetus and then the placenta. This is divided into the first stage of labor (opening stage), the second stage of labor (expulsion stage), and the third stage of labor (afterbirth stage).

(1) Opening stage This is the stage when the cervix and cervical opening open, and first regular uterine contractions (labor pains) are observed. This is open labor, and the initial contractions last for about 15 seconds, with intervals of about 20 minutes. This causes tissues to stretch from the lower part of the uterus (the part corresponding to the isthmus of the uterus) to the cervix, and as the cervix opens, part of the amniotic membrane is detached from the uterine wall, causing mucus mixed with blood (bloody vaginal discharge) to come out. This is the start of labor, and is commonly known as the birth sign. Amniotic fluid is forced into the space between the detached amniotic membrane and the fetal head, i.e. the presenting part of the fetus, with each contraction, increasing in volume and forming a vesicle. This is called the amniotic sac, and it enters the birth canal in place of the fetal head, opening the cervix. This state is similar to the way a long, thin rubber balloon is inflated; the tip inflates first, then it gradually progresses towards the mouth as the balloon inflates. As the contractions become stronger and longer, and the intervals between contractions become shorter, the amniotic sac grows larger and the part that will become the birth canal opens up, until the amniotic membrane breaks and the amniotic fluid (pre-amniotic fluid) inside the amniotic sac leaks out. This is called water rupture, and is usually when the cervix opens completely (full dilation), making it impossible to distinguish between the cervix and the uterine body, and the vaginal part of the uterus has almost disappeared and receded. This process is called the first stage of labor. If the cervix is stiff and difficult to dilate, drugs are used to soften it and make it easier to dilate.

(2) Expulsion stage This is the period from when the membranes rupture and the cervix is fully dilated until the fetus is delivered. The labor pains are strongest, and since abdominal pressure (pushing) is also added, these labor pains are also called co-compression labor pains. The part of the fetus that is the most advanced, that is, the presenting part (in normal delivery, the head), descends deep into the pelvic cavity, and after the membranes rupture, abdominal pressure is unconsciously applied to directly open the birth canal. In other words, the woman begins to push, facilitating the delivery of the fetus. Eventually, part of the presenting part can be seen between the vulva slits from the outside during the contractions, and recedes and becomes hidden during the intermittent contractions. This state is called expulsion. As this is repeated several times, the appearance of the presenting part gradually increases, and eventually it remains exposed outside the vulva even during the intermittent contractions. This is called exposure. In normal childbirth, the baby's head is delivered first, followed by the left and right shoulders, one behind the other, and then the trunk and limbs are delivered, and amniotic fluid mixed with some blood flows out. This is the second stage of childbirth, and once the amniotic fluid has flowed out, the mother suddenly feels more comfortable, and labor pains become intermittent for a while.

(3) Afterbirth: After the delivery of the fetus, the placenta is delivered together with the amniotic membrane and umbilical cord. The labor pains that had been dormant begin to reappear about 10 to 15 minutes after the delivery of the fetus. These pains are called afterbirth pains, and are shorter in duration and longer in frequency than those in the labor stage. The pain is also milder. This allows the delivery of the placenta to proceed. Immediately after the delivery of the fetus, the blood vessels in the umbilical cord still pulsate, but blood flow eventually stops. Around this time, the uterus begins to contract again, but the internal pressure of the uterus without the fetus suddenly decreases and the contractions become stronger. When the uterine wall where the placenta is attached shrinks strongly with the labor pains, a gap occurs between the contraction of the placenta and the contraction of the placenta, causing the contact surface to move, causing a tear in the decidua and the placenta to detach. At this time, there is bleeding from the placental separation site, known as afterbirth bleeding, and when the placenta and amniotic membrane are eventually delivered along with the umbilical cord, a large amount of blood is suddenly discharged, most of which is blood clots. This marks the completion of childbirth, but the period immediately after delivery is also called the fourth stage of labor, and requires careful observation similar to that during childbirth. In other words, for 2 to 6 hours after the end of childbirth, procedures such as perineal suturing and bathing the newborn are required, and there is a risk of severe bleeding due to atonic bleeding, cervical lacerations, and uterine inversion, so the mother and attendants must be extremely careful.

Looking at the time required for each stage of labor, the opening stage is the longest, taking 10-12 hours for primiparas and 4-6 hours for multiparas. The expulsion stage takes 2-3 hours for primiparas and 1-1.5 hours for multiparas, while the afterbirth stage is short, taking 15-30 minutes for primiparas and 10-20 minutes for multiparas. Looking at all stages, it takes 12-15 hours for primiparas and about half that, 5-8 hours for multiparas.

[Masao Arai]

Birth abnormalities

Childbirth is a natural physiological process, and as long as the mother is healthy and the fetus is developing normally, there is a good chance of an easy birth. In other words, any problems that can be predicted during regular checkups during pregnancy will be treated or prepared for before birth, and even if they are discovered during labor, there is little to worry about as long as the mother is accompanied by a well-equipped maternity hospital or experienced obstetrician-gynecologist.

Abnormalities on the maternal side include narrow pelvis and weak contractions. Weak contractions are when contractions are short and weak, and the intervals between contractions are not urgent. The birth may drag on for two or three days, causing the mother to become extremely fatigued, and forceps delivery or Caesarean section may be necessary. However, natural birth can often be achieved with injections of labor-inducing drugs (such as posterior pituitary preparations) and other measures, so it is desirable not to upset the mother's feelings.

Abnormalities on the fetal side include breech presentation, placental abruption, placenta previa, asphyxiation of the newborn, and birth injury. Placental abruption occurs when the placenta detaches before the fetus is delivered, and can result in the death of the mother due to heavy bleeding. It is common in older women and those who have given birth multiple times, and requires immediate treatment at a hospital that can perform surgery.

[Masao Arai]

Fetus during birth

When a fetus passes through the narrow birth canal and is delivered, the fetal head shows adaptive functions, changing shape and rotating. The fetal skull is still thin, and the sutures that connect the bones are not yet solidified, but are connected by soft tissue. Because of this, when passing through the pelvis, the skull distorts and overlaps at the sutures, making the whole skull elongated and usually with the back of the head protruding, making it easier to pass through. This is called the fetal head's shape-adapting function. The bony birth canal has an opening that is like an oval tube that has been twisted and bent forward halfway through. In contrast, the fetal head is longer in front-to-back diameter than it is wide, and when passing through the bony birth canal, the head rotates around the neck, and when entering the pelvis, the chin is placed on the chest, and when exiting, the head is tilted back in the opposite direction. This sequence is fixed, and is called fetal head rotation.

[Masao Arai]

Newborn baby immediately after birth

The baby is born with a purple-ish skin, but in a normal birth, after a few seconds the baby will cry out, cry loudly, and turn red. First, a thin rubber tube is used to suction the nose, mouth, and trachea, and the umbilical cord is tied with a thread 2-3 cm from the newborn's side and cut on the placenta side. Next, blood and vernix caseosa attached to the newborn are washed off using birth water, and the baby is dressed.

[Masao Arai]

Preparing for childbirth

Preparations for childbirth should be prepared in the final stages of pregnancy, but it is best to follow the instructions of the hospital or maternity hospital where you will be staying. It is advisable to make arrangements for a car to take you to the hospital, especially if you will be staying overnight. In order to eliminate anxiety and fear regarding childbirth, it is necessary to have a certain degree of correct knowledge and mental preparation regarding childbirth, which will not only help you to have a psychologically painless childbirth, but will also help the mother to give birth with a calm attitude.

Next time you give birth, follow the instructions of the doctor, midwife, or other caregiver. It is best to relax during the long opening stage and wait patiently, saving your strength so that you can push hard during the next delivery stage. During the delivery stage, hold something with both hands, take three deep breaths and hold it each time you experience a contraction, and push as hard as you can. Pushing intermittently is not effective, and will only tire you out, preventing you from pushing hard when you really need to. Your caregiver will also give you appropriate instructions on when to push, such as not pushing even during contractions once the baby's head has begun to emerge. Usually, you will stay in your hospital room or waiting room during the opening stage, and when the delivery stage begins, you will be moved to a delivery table in the delivery room. During pregnancy, hospitals and other institutions will give you instructions on how to push and how to rest in a comfortable position.

A birth certificate must be attached to the birth notification form, which must be submitted to the city, town, or village office of the place of birth within 14 days of the birth. A birth certificate is a document prepared by a doctor or midwife who is present at the birth to certify their medical opinion regarding the newborn baby, and there is a section for the birth certificate on the birth notification form. Hospitals also have birth notification forms, so if you submit the form with your seal on your maternal and child health handbook, they will fill in the necessary information on the birth certificate and the maternal and child health handbook.

[Masao Arai]

Childbirth and Health Insurance

Health insurance also applies to childbirth, but because normal childbirth is not considered an illness, it is paid out in the form of a lump-sum birth and childcare allowance, and only abnormal childbirth is considered an illness. Therefore, the determination of whether a childbirth is normal or abnormal is quite strict.

In addition, when an insured person or their spouse gives birth, a lump-sum birth and child care allowance will be paid in an amount determined by government ordinance (as of October 2009, 420,000 yen if the birth is covered by the obstetric medical compensation system, and 404,000 yen if the birth is at a medical institution not covered by the system).

[Masao Arai]

Birth trends

In recent years, ME has been introduced into obstetrics, and obstetrics has made great strides. Analysis of fetal heart sounds and electrocardiograms, ultrasound tomography to detect the presence of the embryo, the implantation site, and the location of the placenta, and Doppler to verify fetal cardiac blood flow are all used in daily diagnoses. By using ultrasound tomography and Doppler in combination, the presence and life of the fetus can be confirmed at 10 weeks of pregnancy. Furthermore, there are labor monitoring devices that use computers to accurately and quickly grasp and process various information from the mother and fetus, and provide the necessary instructions during childbirth. Devices that use ultrasound can grasp the mother's uterine contraction pressure (labor pains), the fetal heart rate, and fetal movements, which are useful for diagnosis and treatment. They are particularly effective in cases where there is a possibility of abnormal childbirth or fetal distress. They can also be used for examinations other than childbirth.

[Masao Arai]

Childbirth customs

Childbirth, along with death, has been seen as a crisis that one must go through in one's life. This is based on the idea of modesty towards the gods, known as the "taboo of childbirth." Childbirth was also a concern not only for the individual and family, but for the entire village. Pregnant women enter a life of taboo from around the time of the obi-iwai ceremony, but when it comes to childbirth, the idea of taboo becomes even stronger, as bleeding is accompanied by the impurity of blood. Depending on the region, the taboo of childbirth is called chiboku, chiimi, akabi, and other names. This corresponds to the taboo of death, such as shiboku and kuro-bi. The "hi" in names such as akabi and sambi stands for fire, and fire was thought to be the most susceptible to impurity, so the fire used to cook food for the newborn had to be kept separate from the fire in the main house and was avoided.

[Yuki Ofuji]

Birthing house

For this reason, birthing huts separate from the main house were built in each household or shared by the community, or in the lower huts or niwa (dirt floors), or bedrooms called nand or heya were used as birthing places. The biggest change in birth customs was in the ubuya (place of birth), which had a long history before becoming the maternity hospitals we know today.

[Yuki Ofuji]

Birth god

The gods who attend the birth room to help and protect during childbirth are called ubusama or ubugamin. Generally, gods were to be avoided during the taboo period around childbirth, but birth gods are special, and are believed to be present during childbirth, protect the mother and newborn, and even control the baby's fate. The gods known as birth gods vary by region, but include mountain gods, broom gods, toilet gods, roadside gods, and rice scoop gods. There are no statues of birth gods, but they are there as if they are there. As soon as the birth is over, ubumeshi (white rice) is cooked and piled high in a bowl, and placed in a tokonoma or cupboard as an offering. Ubumeshi is also offered to the newborn and the woman, and as many women as possible, including midwives and helpers, gather to eat it. The more people involved, the larger the household the newborn will have after it is released into the world.

[Yuki Ofuji]

Midwife

Since childbirth is a natural physiology, in the past there were brave women who gave birth and delivered the baby on their own. Depending on the region, midwives are called various names, such as Toriagebaba, Hikiagebaba, and Kozuebaba. Bringing up and pulling up the baby meant taking the newborn baby into the human world and bringing it into the human community. Old-fashioned midwives did not just help with childbirth, but also played a religious and magical role as the first assistant for the newborn baby as it emerged into the human world. Therefore, the newborn baby and the midwife were considered to have a special relationship throughout their lives.

[Yuki Ofuji]

Method of delivery

Nowadays, birth is usually done lying down, but until the beginning of the Taisho period, birth was generally done sitting down, and it was said that women would die if they gave birth lying down. Difficult births are feared the most, and there are various spells and superstitions.

[Yuki Ofuji]

Ena - Umbilical Cord

The umbilical cord, also called the atzan or placenta, was believed to be the baby's other self, and how it was handled determined the safety of the baby throughout its life. There were various ways to dispose of it.

[Yuki Ofuji]

The customs of various ethnic groups

Childbirth often takes place away from the daily dwelling place. In the San society, a hunter-gatherer people in Africa, pregnant women left their camps alone and gave birth in the bush. In Papua New Guinea, they gave birth on the riverbank. In addition to giving birth in the forest, on the beach, or on the riverbank, they often gave birth in a special hut isolated from the dwelling. In the Marquesas Islands, Tahiti, and Hawaiian Islands in Polynesia, birthing huts were built separately from the dwelling place. In such cases, the birth usually took place with only the pregnant woman and a few attendants. However, it can also take place in public. For example, in ancient Samoa, it was said that births were held in front of 20 or 30 people of all ages and genders, and the children were not chased away. Assistance during childbirth is often provided by women with extensive childbirth experience, as well as the mother of the pregnant woman. Among the Ashanti people of Ghana, women are always looked after by women of maternal kinship, and are not assisted by paternal kinship. Whether or not the husband is present during childbirth varies from society to society. In the society of the Hmong, an ethnic minority group on the Indochina Peninsula, husbands support their wives who are kneeling. Conversely, it is not uncommon for husbands to be absent during childbirth. In the Royal Islands of Melanesia, childbirth is a kind of spectacle, and men, women, and children gather to watch, but the husband is not present, and does not visit his wife and child after birth until the baby is able to crawl. Pregnant women are isolated during childbirth because childbirth, and especially the blood that flows during it, is considered impure and dirty, or to have dangerous powers.

Sometimes the husband is treated the same as well as the wife. The Arapesh people of New Guinea build a seclusion hut on the lowlands away from the village on the plateau, and give birth there. After giving birth, the mother and child move to another temporary hut halfway between the village and the birth hut. The husband is not allowed to enter the temporary hut for the first four days, and on the fifth day he is allowed to meet the mother after undergoing a purification ceremony. After a few more days, both the husband and wife are purified and return home. However, for one month after the birth, both the mother and husband must stay at home, after which a banquet is held and they are freed from the taboo. In Costa Rica, the mother lives in a seclusion hut for one month after giving birth, during which time food is cooked and carried by other women and given to them on the end of a stick. This is because it is believed that anyone who touches the tools used by the mother will die. In Tahiti, the mother is also not allowed to touch food with her hands, and other people feed it to her. One famous childbirth custom is the couvad (fake birth). During the birth, the husband lies on the bed, suffers, follows various taboos, and is treated like a new mother by those around him and given careful care. This is seen in the Basque region of Spain, parts of the Baltic coast, and some indigenous peoples of North, Central, and South America. In addition to lying down, the mother is often in a sitting or kneeling position during childbirth.

Among the items that are handled with care at birth are the afterbirth (placenta, etc.) and the umbilical cord. These are believed to affect the fate of the newborn, and are disposed of according to custom, but the way they are disposed of often differs depending on whether the baby is a boy or a girl. Among the nomadic Hadendwa people of Sudan, the afterbirth of a boy is buried in the shade of a tree far away from the camp, while the afterbirth of a girl is buried inside the tent. In Bali, the afterbirth of a boy is buried to the right of the entrance to the house, and that of a girl to the left. The Hmong people bury the umbilical cord under the doorway of the house for boys and under the leg of the bed for girls. In Samoa, the umbilical cord of a boy is thrown into the sea or buried under taro. The umbilical cord of a girl is buried under a tree that is used to make tapa cloth. After birth, rituals are often performed for the newborn child. The Tzotzil-speaking Maya of Mexico chant while placing a hoe, axe, or machete over the baby's mouth for boys, and corn, chili pepper, salt, or weaving tools over the baby's mouth for girls. These are thought to be meant to position the differences between men and women in the world view and to confirm the roles of men and women. Some people do not give babies colostrum, and believe that the first milk a baby drinks must come from a woman other than its mother. For example, the Kun, a San tribe in Africa, believe that if a baby drinks its mother's milk too soon, both the mother and child will die, so they feed the baby milk from another woman first.

Thus, childbirth is surrounded by many beliefs, taboos, and rituals. This is because childbirth is not only dangerous to the mother, but also has important social significance. Through childbirth, a woman acquires the role of a mother, and is sometimes recognized as a true wife. In some societies, marriage is only established after the birth of the firstborn child. Of course, for a man, it means becoming a father. Birth rites express this acquisition of a new social status or change in status in the form of a ritual. On the other hand, childbirth is the birth of a child, and birth rites have the meaning of confirming and positioning the newborn child as a member of society. Van Gennep considers childbirth to be one of the stages that humans must pass through in life, and the rituals for childbirth, like other rites of passage, consist of three stages: isolation, transition, and integration. The birth process of the Arapesh people mentioned above is one example.

[Itabashi Masami]

"Travels and Legends, No. 6, No. 7, Birth and Funeral Issue" (1933, Sangensha) ▽ "Family Chats" (included in The Complete Works of Yanagita Kunio Vol. 15, 1963, Chikuma Shobo) ▽ "Infant Medication, by Ofuji Yuki (1985, Iwasaki Bijutsusha)" ▽ "Clinical Practice of Obstetrics, by J. W. Dudenhausen and W. Silimbel, translated by Suzuki Shigenori et al. (1994, Nishimura Shoten)" ▽ "Ideal Childbirth and the History of Childbirth - History of Obstetric Medicine in Japan, by Sekiguchi Masao (1998, Japan Publishing Association)" ▽ "The History of Childbirth, by Sugitate Yoshikazu (Shueisha Shinsho)"

Position of the fetus, surrounding organs, and pelvis just before birth
©Shogakukan ">

Position of the fetus, surrounding organs, and pelvis just before birth

Childbirth progress
©Shogakukan ">

Childbirth progress

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

出産とは子供を産むことで、医学的には、妊娠中の母体の子宮内で一定期間、発育してきた胎児および付属物（臍帯(さいたい)、胎盤、卵膜、羊水）を陣痛と腹圧による娩出(べんしゅつ)力で外界に排出する現象をいい、分娩とよぶ。分娩中の女性が産婦であり、初めて分娩するものを初産婦、すでに分娩の経験をもつものを経産婦という。また、19歳以下の初産婦を若年初産婦、35歳以上の初産婦を高年初産婦とよび、5回以上の経産婦を多産婦という。なお、世界保健機関（WHO）では35歳以上の初妊婦を高年初妊婦としている。

［新井正夫］

分類

分娩にはいろいろな種類がある。在胎週数による分類では、37週から41週までの分娩を正期産、36週以前の分娩を早産、42週以後の分娩を過期産に分け、早産はさらに24週から36週までの分娩を狭義の早産、24週までの分娩を流産とよんでいる。分娩経過の分類では、経過が順調で母児ともに健全なものを正常分娩といい、経過が異常で母児の危険を伴うものを異常分娩とよぶ。一般に分娩の三大要素として、骨産道と軟産道とからなる産道、陣痛と腹圧とからなる娩出力、胎児およびその付属物の三つがあげられているが、これらのうちのいずれかに異常があれば分娩の進行が妨げられて異常分娩となる。人工介助の有無からは自然分娩と人工分娩に分ける。また、胎児数によって、一つの場合を単胎分娩、二つ以上の場合を多胎分娩とよび、多胎分娩はその数に応じて双胎分娩や品胎（三胎）分娩などという。新生児の生死によっても、生産と死産に分ける。

　なお、俗に安産というのは正常分娩で自然分娩の場合をさしており、異常分娩は難産とよばれる。ここでは正常分娩を中心に述べる。

［新井正夫］

出産経過

分娩は規則正しい子宮の収縮、すなわち分娩陣痛（約10分間隔）をもって始まり、閉鎖している子宮頸管(けいかん)の開大を経て、まず胎児、ついで胎盤の娩出をもって終了する。これを分娩第1期（開口期）、分娩第2期（娩出期）、分娩第3期（後産(こうざん)期）に分ける。

(1)開口期　子宮頸管および子宮口が開大する時期で、まず規則正しく子宮の収縮（陣痛）がみられる。これが開口陣痛で、最初は発作が約15秒、間欠が約20分間くらいである。これによって子宮下部（子宮峡部に相当する部分）から子宮頸管にかけて組織が伸展し、子宮口が開大されるとともに卵膜の一部が子宮壁から剥離(はくり)され、そのために血液の混じった粘液（血性帯下(けっせいたいげ)）が出てくる。これが出産開始で、俗に「しるし」があったといわれる産徴である。この剥離した卵膜と、胎児の児頭すなわち先進部との間には羊水が陣痛発作のたびに圧入されて増量し、胞状を呈する。これを胎胞といい、これが児頭のかわりに産道に突入し、子宮口を開大していく。この状態は、細長いゴム風船を膨らませるとき、先端部がまず膨らみ、それがだんだん口元のほうに進行しながらゴム風船が膨らんでいくありさまに似ている。陣痛発作はますます強く、しかも長くなり、間欠が短くなってくると、胎胞も大きくなるとともに産道となる部分が開大してきて、ついには卵膜が破れて胎胞内の羊水（前羊水）が流出する。これを破水といい、普通は子宮口が完全に開いて（全開大）子宮頸管と子宮体部との区別がつかず、子宮腟(ちつ)部がほとんど消失展退したときであって、ここまでの経過を分娩第1期とよんでいる。なお子宮頸管が堅くて開大しにくい場合には、それを柔軟にして開大しやすくする薬剤が使われる。

(2)娩出期　破水および子宮口の全開大後、胎児を娩出するまでの期間で、分娩陣痛はもっとも強く、腹圧（いきみ）も加わるので、この娩出陣痛は共圧陣痛ともよばれる。胎児の体のうちもっとも先に進んでいる部分、すなわち先進部（正常分娩では頭部）は骨盤腔(こつばんくう)内に深く下降しており、破水後は直接産道を開大していくために、腹圧が無意識に加わる。すなわち、いきむようになって胎児の娩出が促進される。やがて陣痛発作時に外部からも陰裂の間に先進部の一部が見え、間欠時には後退して隠れてしまうようになる。この状態を排臨という。これを数回繰り返すうちに先進部の現れ方がしだいに大きくなり、ついには陣痛間欠時にも陰裂外に露出したままとなる。これを発露という。正常分娩では、このようにしてまず児頭が娩出され、続いて左右の肩が前後して現れ、躯幹(くかん)および四肢が娩出されるとともに、多少の血液を混じた後羊水(こうようすい)が流出する。ここまでが分娩第2期で、後羊水が流出してしまうと産婦は急に楽になり、陣痛もしばらく間欠する。

(3)後産期　胎児の娩出完了後、胎盤を卵膜および臍帯とともに娩出するまでの時期で、休止していた分娩陣痛が胎児娩出後、約10～15分経過すると新たに発現する。これを後産陣痛といい、娩出期より発作が短く、間欠は長い。また、痛みは軽い。これによって胎盤の娩出が進行する。すなわち、胎児娩出の直後は臍帯中の血管にはまだ拍動があるが、やがて血行が停止する。そのころに子宮はふたたび収縮を始めるが、胎児のいなくなった子宮では内圧が急に減少して収縮の度合いが強く、陣痛発作とともに胎盤付着部の子宮壁が強く縮小すると、胎盤の縮小との間にずれを生じて接面が移動し、脱落膜に断裂をおこして胎盤が剥離するようになるわけである。このとき、後産出血といって胎盤剥離面からの出血があり、胎盤と卵膜が臍帯とともにやがて娩出されると、いちじに多量の血液が排出されるが、これは大部分が凝血である。これをもって出産は完了したことになるが、分娩直後は分娩第4期ともよばれるほど分娩と同じような注意深い観察が必要とされる。すなわち、分娩終了後2～6時間は会陰(えいん)縫合や新生児の沐浴(もくよく)などの処置もあり、弛緩(しかん)出血、頸管裂傷、子宮内反症などによる大出血の危険性があるので、産婦および介助者は十分に用心する必要がある。

　なお、分娩所要時間を各期ごとにみると、開口期がもっとも長く、初産婦で10～12時間かかるが、経産婦では4～6時間である。娩出期は初産婦で2～3時間、経産婦で1時間から1時間半、後産期は短時間に終わり、初産婦でも15分から30分、経産婦で10～20分である。全期間を通じてみると、初産婦では12～15時間かかり、経産婦の場合は約半分の5～8時間で終わる。

［新井正夫］

出産の異常

出産は自然の生理であり、母体が健康で胎児の発育が順調であれば安産が十分に期待できる。すなわち、妊娠中の定期検診で予知できるものは出産前に処置されたり準備されるし、分娩経過中に発見されるものでも、設備の整った産院や病院、経験豊富な産婦人科医が付き添う限り、心配はほとんどないといえる。

　母体側に異常のあるものとしては狭骨盤や微弱陣痛などがある。微弱陣痛というのは陣痛発作が短くて弱く、間隔も切迫してこない場合をいい、出産が長引いて2日も3日もかかることがあるので母体が極度に疲労し、鉗子分娩(かんしぶんべん)や帝王切開を必要とすることがある。しかし、陣痛促進剤（下垂体後葉製剤など）の注射、その他の処置で自然分娩が行われることも多いので産婦の気持ちを動揺させないことが望まれる。

　胎児側に異常のあるものとしては骨盤位（さかご）をはじめ、常位胎盤早期剥離や前置胎盤などがあり、さらに新生児の窒息仮死や分娩損傷などがあげられる。常位胎盤早期剥離は胎児が娩出される前に胎盤がはがれるもので、大出血のために産婦が死亡することがある。高年期の産婦や経産婦に多く、手術可能な病院での早急な対処が必要である。

［新井正夫］

出産中の胎児

狭い産道をくぐり抜けて娩出される胎児には、児頭が形を変えたり回旋したりする適応機能がみられる。胎児の頭蓋(とうがい)はまだ薄くて骨と骨の継ぎ目である縫合(ほうごう)も固まらずに柔らかい組織でつながっている。このために骨盤中をくぐり抜けるときには、頭蓋骨がゆがんだり縫合部で重なり合ったりして、頭蓋全体が細長く、普通は後頭部が突出した形になって通過しやすくなる。これを児頭の応形機能とよんでいる。また骨産道は、長円形の管をねじりながら途中で前方に曲げたような形の切り口をしている。児頭はこれに対して横幅より前後径が長く、骨産道を通過するには頸部を軸にして頭を回旋させながら進み、骨盤に入るときにはあごを胸につけ、出るときには逆に頭を反らせながら生まれてくる。この順序は決まっており、児頭回旋という。

［新井正夫］

出産直後の新生児

全身紫色に似た肌で生まれるが、正常分娩では何秒かののちに産声(うぶごえ)を発し、大声で泣き出すとともに肌が赤くなってくる。まず、細いゴム管で鼻や口、気管内の吸引を行い、臍帯を新生児側から2～3センチメートルのところを糸で結び、胎盤側で切断する。次に産湯を使って、新生児に付着している血液や胎脂などを洗い落とし、着衣させる。

［新井正夫］

出産への備え

出産の準備用品などは妊娠末期に用意しておくが、入院する病院や産院の指示に従うのがよい。とくに夜間入院するときを考慮して、入院用の車の手配なども準備しておくことが望ましい。分娩に対する不安や恐怖をなくすためにも、分娩についての正しい知識と心構えをある程度もつことが必要で、精神的な無痛分娩のためばかりでなく、産婦自身が落ち着いた態度で出産するためにも役だつ。

　次に出産に臨んだら、医師や助産師らの介助者の指示に従うようにする。長時間にわたる開口期は楽な気持ちで過ごし、次の娩出期に十分ないきみができるように力を蓄えてゆっくり待つのがよい。娩出期には両手で何かを握り、陣痛発作のたびに三息ほど深く息を吸って止め、思いきりいきむようにする。間欠時にいきんでも効果はなく、かえって疲れるだけで、本当のいきみが必要なときに十分にいきむことができなくなる。また、児頭が発露しだしたら陣痛発作時でもいきまないなど、いきむタイミングについては介助者が適宜指示してくれる。普通は開口期段階には病室または控室で過ごし、娩出期になって分娩室の分娩台に移される。なお、いきみ方や楽な姿勢で休む方法などについては、妊娠中に病院などで指導がある。

　出産後14日以内に出生地などの市区町村役場へ提出する出生届(しゅっしょうとどけ)には、出生証明書を添付することになっている。出生証明書は、医師または助産師が自ら出産に立ち会った場合にその出生児に対する医学的判断を証明するために作成する文書であるが、出生届には出生証明の欄がある。病院にも出生届用紙が備えてあるので、母子健康手帳に印鑑を添えて出すと、出生証明の欄と母子健康手帳にそれぞれ必要事項を記入してくれる。

［新井正夫］

出産と健康保険

健康保険は出産にも適用されるが、正常分娩は病気ではないので出産育児一時金という形で給付され、病気扱いになるのは異常分娩の場合に限られる。したがって、正常分娩か異常分娩かの判定は相当に厳密である。

　なお、被保険者もしくはその配偶者が分娩した場合、出産育児一時金として政令で定める額（2009年10月現在、産科医療補償制度対象分娩の場合は42万円、同制度に加入していない医療機関等で分娩の場合は40万4000円）が支給される。

［新井正夫］

出産の動向

近年は産科方面にもMEの導入が行われ、産科学は飛躍的に進歩してきた。胎児の心音や心電図の分析、また超音波断層法による胎芽の存在、着床部位や胎盤の位置の認知をはじめ、ドップラー法による胎児心血流の証明などは日常の診断に活用されている。超音波断層法とドップラー法を併用すれば、妊娠10週で胎児の存在と生死を確認できる。さらに分娩に際しては、母体側と胎児側からのいろいろな情報をコンピュータによって的確・迅速に把握、処理して、必要な指示の得られるような分娩監視装置もある。超音波を利用した装置で、母体の子宮収縮圧（陣痛）、胎児の心拍数、胎動を把握することができ、診断・治療に役立つ。とくに異常分娩や胎児仮死の可能性がある場合にはきわめて有効である。分娩時以外にも、検査のために用いることがある。

［新井正夫］

出産に関する習俗

出産は人の一生のなかで、その死とともに、通過しなければならない一つの危機としてとらえられてきた。それは「産の忌み」という神に対する慎みの観念によっている。また出産は一身一家だけではなく、村全体の関心事でもあった。妊婦は帯祝いのころから忌みの生活に入るのであるが、いよいよ出産というときは、出血という血のケガレを伴うので、一段と忌みの観念が強まった。産の忌みは地方によって、チボクとかチイミ、アカビなどいろいろな呼び方がある。これは死の忌みのシボク、クロビなどに対応する。アカビ、サンビなどのヒは火であって、火がもっともケガレを受けやすいと考えられ、産婦の煮炊きの火は、母屋の火とは別火(べっか)として避けねばならなかった。

［大藤ゆき］

産屋(うぶや)

このため母屋(おもや)とは別棟の産小屋を、各戸または集落共同に設けたり、下屋(げや)やニワ（土間）に設けたり、ナンドとかヘヤといわれる寝室が産所に使われた。出産の習俗のなかでいちばん大きく変わったものはウブヤ（産む場所）で、現在の産院となるまでには長い歴史があった。

［大藤ゆき］

産神

産室に臨んで出産を助け守ってくれる神をウブサマ、ウブガミなどとよぶ。一般に神は産の忌みの間は避けねばならぬものであったが、産神だけは特別で、産に立ち会い、産婦と生児を守り、生児の運命までもつかさどる神として信じられている。産神といわれる神は土地によって異なるが、山の神、箒(ほうき)の神、便所神、道祖神、しゃもじ神などがある。産神は神像はないが、そこにおられるものとして、出産が終わるとすぐにウブメシ（白いご飯）を炊き、茶碗(ちゃわん)に山盛りにして、床の間や戸棚の中などに供える。ウブメシは生児、産婦にも供え、産婆や手伝いの人などなるべく多くの女たちに集まって食べてもらう。その人数が多いほど生児が世に出てから大世帯をもつという。

［大藤ゆき］

産婆

出産は自然の生理なので、以前は一人で産んで一人で取り上げたという気丈な人があった。産婆は地方によってトリアゲババ、ヒキアゲババ、コズエババなど、さまざまな呼び方がある。取り上げ、引き上げというのは、生まれ出る子を人間界に取り上げる、人間の仲間に引き入れ加えるという意味があった。古風な産婆はただ分娩(ぶんべん)の手助けをするだけでなく、生児にとっては人間界に現れるための第1番目の補助者という、宗教的な呪術(じゅじゅつ)的な役割をもつものであった。したがって生児と産婆とは一生を通じて特別の関係にあるものとされていた。

［大藤ゆき］

分娩の方法

いまでは仰臥産(ぎょうがさん)であるが、大正の初めごろまでは座産(ざさん)が一般であり、寝て産をすると死ぬといわれていた。難産をもっとも恐れ種々のまじないや俗信がある。

［大藤ゆき］

えな・へその緒

アトザンとか胎盤とよばれるえな、臍帯(さいたい)は、生児の分身であり、その取り扱い方によって、生児の一生の安危にかかわるものと信じられていた。その始末法にはさまざまの作法があった。

［大藤ゆき］

諸民族の習俗

出産は日常の住居から離れた場所で行われることが多い。アフリカの採集狩猟民サンの社会では妊婦は一人で野営地を離れ、やぶの中で産んだ。パプア・ニューギニアでは河原で出産した。このように森の中、海岸、川岸などで出産したほか、しばしば出産のための特別な小屋に隔離されて出産した。ポリネシアのマルケサス諸島、タヒチ、ハワイ諸島などでは住居とは別の産小屋を建ててそこで産んだ。そのような場合たいてい妊婦とごく少人数の介添えだけで行われる。しかし公衆の面前で行われる場合もあり、たとえばかつてのサモアでは老若男女20人か30人の前で行われ、子供も追い払われなかったという。出産の手助けは出産経験の豊富な女性のほか、妊婦の母が行うことが多い。ガーナのアシャンティ人ではかならず母系親族の女性の世話を受け、父系親族の者からは助けを受けない。出産時に夫が同席するか否かは社会によって異なる。インドシナ半島の少数民族モンの社会では夫はひざまずいた姿勢をとった妻を支えてやる。逆に出産時の夫の不在例もよくみられる。メラネシアのロイヤル諸島では出産は一種の見せ物で、男も女も子供も見に集まるが、夫だけはおらず、出産後も子がはいはいができるようになるころまで妻子のところを訪れない。出産時の妊婦の隔離は、出産、とくにそのとき流れる血を不浄、穢(けがれ)と考えたり、危険な力をもっていると考えるからである。

　妻だけでなく夫も同様に扱われることもある。ニューギニアのアラペシュ人は台地の上にある集落から離れた低地に隔離小屋を建て、そこで出産する。出産後、母子は集落と出産小屋の中間にある別の仮小屋へ移る。夫は最初の4日間仮小屋へ入れず、5日目に清めの儀礼を受けてから会う。さらに数日後に夫婦とも清めをしてから自宅へ戻る。しかし産後1か月間は産婦はもちろん夫も自宅にこもっていなければならず、そのあと宴会を開き、禁忌から解放される。コスタリカでは産婦は産後1か月隔離小屋で暮らすが、その間、食物は他の女性が調理して運び、棒の先に刺して与えた。産婦が使った道具に触れた人間は死んでしまうと考えるからである。タヒチでも産婦は食物に手を触れてはならず、他の者に食べさせてもらった。出産の習俗として有名なものにクーバード（擬娩(ぎべん)）がある。妻の出産時に夫も床について、苦しんだり、さまざまな禁忌に従ったり、周囲の人たちから産婦のように扱われ、手厚い世話を受ける。スペインのバスク、バルト海沿岸の一部、北米・中米・南米のいくつかの先住民族などにみられる。なお、出産時の産婦の姿勢は、寝た形のほか、座ったりひざまずいた姿勢がよくみられる。

　出産時に注意深く扱われるものに胎盤などの後産(あとざん)とへその緒がある。これらは生まれた子の運命に影響を及ぼすと考えられ、慣習に従った処理がなされるが、しばしば生まれた子が男か女かによって処理の仕方が異なる。スーダンの遊牧民ハデンドワでは、男児の後産はキャンプから遠く離れた木陰に埋められ、女児の後産はテントの内部に埋められる。バリ島では後産を男の子の場合は家の入口の右側に、女の子なら左側に埋める。モン人はへその緒を男の子なら家の戸口の下、女なら寝台の脚の下に埋める。サモアでは男の子のへその緒は海に投げたりタロイモの下に埋めた。女の子のへその緒はタパ布の材料になる木の下に埋める。出産後、生まれた子供に儀礼を施すこともよくなされる。メキシコのツォツィル語系マヤ人では男の子の場合は鍬(くわ)、斧(おの)、山刀、女の子の場合はトウモロコシ、トウガラシ、塩、機織(はたお)りの道具を赤ん坊の口に当てて唱え言をいう。これらは男女の違いを世界観のなかで位置づけ、男女の役割を確認することを意味していると考えられる。なお、初乳を赤ん坊に飲ませないとか、赤ん坊が最初に飲む乳は母親以外の女性の乳でなければならないとする所がある。たとえばアフリカのサン人の部族クンでは赤ん坊がすぐ母親の乳を飲むと母子ともに死ぬと信じているので、最初は他人の女性の乳を飲ませる。

　このように出産は多くの信仰、禁忌、儀礼に取り囲まれている。それは、出産が母体にとって危険であるというだけでなく、社会的にも重要な意味をもっているからである。出産を経て、女性は母としての役割を獲得し、ときには真に妻として認知される。というのは、初生児の出産後、初めて婚姻が成立する社会もあるからである。もちろん男にとっては父になることを意味する。出産儀礼はこのような新しい社会的地位の獲得、あるいは地位の変化を儀礼という形で表している。他方、出産は子供にとっての出生であり、誕生の儀礼は生まれた子を社会の一員として確認し、位置づける意味をもっている。なお、ファン・ヘネップは、出産・出生を人間が一生のうちに通過しなければならない段階の一つとしてとらえ、その際の儀礼は他の通過儀礼と同じく、隔離、移行、統合の3段階からなるとした。先に述べたアラペシュ人の出産経過はその一例である。

［板橋作美］

『『旅と伝説　六ノ七　誕生と葬礼号』（1933・三元社）』▽『「家閑談」（『定本柳田国男集15』所収・1963・筑摩書房）』▽『大藤ゆき著『児やらい』（1985・岩崎美術社）』▽『J・W・ドゥデンハウゼン、W・シリンベル著、鈴木重統ほか訳『産科臨床プラクティス』（1994・西村書店）』▽『関口允夫著『理想のお産とお産の歴史――日本産科医療史』（1998・日本図書刊行会）』▽『杉立義一著『お産の歴史』（集英社新書）』