Obstetrics (from the Latin obstare, "to stand by") is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth). Almost all modern obstetricians are also gynaecologists; see Obstetrics and gynaecology.

Antenatal care

In obstetric practice, the obstetrician will see a pregnant woman on a regular basis as her pregnancy progresses. The exact schedule varies depending on resources and risk factors, such as diabetes.

The main rationale for these visits is surveillance for diseases of pregnancy which are detectable. Some examples are:

1. pre-eclampsia. The blood-pressure and urine of a pregnant woman is checked at every opportunity to check for this
2. placenta praevia. On ultrasound, the placenta is visible obstructing the birth canal
3. abnormal presentation (late pregnancy only). The foetus may be feet-first (breech), side-on (transverse), or at an angle (oblique presentation)
4. IUGR (Intrauterine Growth Restriction) , this is a general designation, where the foetus is too small for its gestational age. Causes can be intrinsic (in the foetus) or extrinsic (usually placental problems). IUGR refers to fetal growth that is less than 10% of what is expected at that gestational age.

Induction

An obstetrician may recommend a woman have her labour induced if it is felt that continuation would be more dangerous to her, the foetus, or both. Reasons to induce include:

1. pre-eclampsia
2. IUGR
3. diabetes
4. other general medical condition, such as renal disease

Induction can occur any time after 24 weeks of gestation if the risk to the fetus or mother is greater than the risk of delivering a premature fetus regardless of lung maturity. Prior to 32 weeks gestation steroids are given to the mother to help mature the fetus's lungs.

If a woman does not eventually labour by 41-42 weeks, induction is performed, as the placenta becomes unstable after this date.

Induction is achieved by 3 methods:

1. pessary of Prostin cream, prostaglandin E₂
2. surgical induction, by piercing the amnion
3. infusion of oxytocin

Labour

During labour itself, the obstetrician may be called on to do a number of things:

1. monitor the progress of labour, by reviewing the nursing chart, performing vaginal examination, and assessing the trace produced by a foetal monitoring device (the cardiotocograph)
2. accelerate the progress of labour by infusion of the hormone oxytocin
3. provide pain relief, either by nitrous oxide (nowadays uncommon), opiates, or by epidural anesthesia done by anaethestists)
4. surgically assisting labour, by forceps or the Ventouse (a suction cap applied to the foetus' head)
5. Caesarean section, if vaginal delivery is decided against or appears too difficult. Caesarean section can either be elective, that is, arranged before labour, or decided during labour as an alternative to hours of waiting. True "emergency" Cesarean sections (where minutes count) are a rarity.
6. In the US, obstetric routine often includes a circumcision of the newborn. This procedure removes the foreskin of the male.

Emergencies in obstetrics

Two main emergencies are eclampsia and ectopic pregnancy.

Ectopic pregnancy is when an embryo implants in the Fallopian tube or (rarely) on the ovary or inside the peritoneal cavity. Tubal pregnancies are very dangerous, as at about 4-10 weeks the tube bursts, causing massive internal bleeding.

Ectopic pregnancy must be considered in any woman with abdominal pain who has the slightest chance of being pregnant. Diagnosis is by a positive pregnancy test and a uterus empty on ultrasound. Treatment is by laparoscopy, and the tube is incised and excavated.

Pre-eclampsia is a disease caused by mysterious toxins secreted by the placenta. These toxins act on the vascular endothelium, causing hypertension and proteinuria. If severe, it progresses to fulminant pre-eclampsia, with headaches and visual disturbances.

This is a prelude to eclampsia, where a convulsion occurs, which is often fatal.

The only treatment for eclampsia, or advancing pre-eclampsia is delivery, either by induction or Caesarean section. Women can be stabilised temporarily with magnesium sulphate. Delivery as early as 28 weeks is not unknown.

See also

• List of obstetric topics
• Home birth
• Midwifery
• Obstetric ultrasonography