OVERVIEW

What is postterm pregnancy?

Postterm pregnancy refers to a pregnancy that has reached or exceeded 42 weeks of gestation without delivery. Gestational age can be calculated based on the mother's last menstrual period or estimated through obstetric ultrasound.

Postterm pregnancy indicates the fetus has remained in the uterus for too long. Staying in the womb longer is not necessarily better. After 40 weeks of pregnancy, placental function begins to decline. Postterm pregnancy increases neonatal mortality and the likelihood of health complications, requiring medical intervention.

Typically, after 41 weeks of gestation, doctors will begin monitoring the fetus and assess whether medical intervention is needed to induce labor.

Is postterm pregnancy common?

It occurs in about 3%–15% of pregnancies, making it relatively common. However, as medical understanding of postterm pregnancies has improved and interventions to assist delivery have become more widespread, the incidence has decreased. Data from other countries show postterm pregnancy rates ranging from 0.3% to 8.5%.

SYMPTOMS

What are the symptoms of post-term pregnancy?

No onset of contractions by 42 weeks of pregnancy. If fetal abnormalities occur, there may also be sudden reduction in amniotic fluid, decreased fetal movement, and other symptoms.

What adverse effects can post-term pregnancy cause?

• Excessive fetal weight. For the mother, this increases the risk of dystocia, potentially raising the likelihood of cesarean section, postpartum hemorrhage, and birth canal lacerations. For the baby, it may lead to complications such as neonatal asphyxia, clavicle fracture, brachial plexus injury, cephalohematoma, meconium aspiration, etc.
• Placental insufficiency. This can result in low fetal weight, leading to the baby being small for gestational age or a term small-for-gestational-age infant. It may also cause complications like neonatal hypoglycemia, polycythemia, asphyxia, and meconium aspiration.

Does post-term pregnancy have any sequelae?

Post-term pregnancy does not cause long-term physical sequelae for the mother.

However, women who have experienced post-term pregnancy once are more likely to have it again in subsequent pregnancies.

CAUSES

What are the common causes of post-term pregnancy?

The exact causes of most post-term pregnancies remain unclear, but pregnant women with the following conditions have a higher likelihood of experiencing post-term pregnancy:

• First pregnancy;
• Previous history of post-term pregnancy;
• Maternal obesity;
• Advanced maternal age;
• Rare fetal developmental abnormalities, such as anencephaly or adrenal gland malformations.

DIAGNOSIS

What tests are needed for post-term pregnancy?

• Assessing fetal status: Includes color Doppler ultrasound to evaluate umbilical cord blood flow, amniotic fluid volume, fetal heart rate monitoring, fetal movement counting, etc.
• Assessing maternal status: Evaluates cervical maturity (Bishop cervical score), etc.

Why are these tests performed for post-term pregnancy?

Post-term pregnancy may lead to abnormal fetal blood flow, causing fetal hypoxia and ischemia, or reduced amniotic fluid volume, compromising fetal safety. Therefore, frequent fetal monitoring is necessary. If signs of intrauterine hypoxia or ischemia are detected, prompt delivery (termination of pregnancy) should be initiated.

If the mother's cervical maturity meets the criteria, vaginal delivery is possible. If cervical maturity is insufficient, cervical ripening or cesarean section may be considered to assist delivery.

TREATMENT

Which department should I visit for post-term pregnancy?

Obstetrics.

Can post-term pregnancy be delivered vaginally?

Post-term pregnancy can still be delivered vaginally and does not necessarily require a cesarean section. The delivery method depends on factors such as the baby's weight, the mother's birth canal condition, and the overall status of both mother and fetus during labor.

However, if the baby shows signs of emergency conditions like hypoxia or ischemia, vaginal delivery should not be attempted. Instead, a cesarean section should be performed promptly to terminate the pregnancy and avoid serious harm to the baby.

How is post-term pregnancy treated?

• If there are no signs of labor by 41 weeks of pregnancy, obstetricians may recommend medical induction, most commonly using oxytocin. Artificial rupture of membranes (AROM) may also be performed to stimulate contractions. AROM involves manually breaking the amniotic sac to release amniotic fluid, which can help initiate labor.
• If cervical ripening is insufficient, doctors may use various methods to promote cervical maturation to facilitate delivery.
• If waiting for spontaneous labor is preferred, pregnant women beyond 41 weeks should closely monitor fetal changes as instructed by their doctor. Generally, waiting beyond 41 weeks and 6 days is not advised.
• If natural delivery is not feasible due to maternal or fetal conditions, such as fetal hypoxia or ischemia, doctors will promptly perform a cesarean section to deliver the baby.

What should post-term pregnant women pay attention to during hospitalization?

• Before delivery: Prepare identification documents and a delivery bag, and follow the doctor's treatment plan. Since delivery is highly physically demanding and a cesarean section may be necessary for post-term pregnancy, psychological preparation is essential.

• After delivery: Family members should take care of the mother, ensuring she gets adequate rest and minimizing unnecessary visits. If the mother can eat, provide easily digestible food. Monitor postpartum lochia discharge and seek medical help if excessive bleeding occurs. The mother's clothing should be breathable and comfortable, and changed regularly.

Do post-term pregnant women need follow-up after discharge?

If there are no other complications, a postpartum check-up should be scheduled at the obstetrics department 42 days after delivery to assess the mother's recovery. The baby should also undergo a health check-up at 42 days.

DIET & LIFESTYLE

What should expectant mothers with post-term pregnancy pay attention to in their diet?

The diet before delivery is the same as for regular expectant mothers. However, if overweight, attention should be paid to controlling the intake of fats and carbohydrates, opting for a high-protein diet.

Post-delivery dietary considerations are also the same as for other breastfeeding mothers. Foods rich in protein, calcium, and iron are the top choices. A varied diet with a balanced combination of meat and vegetables is recommended. Overly greasy soups contain excessive fat but lack other nutrients, so they are not recommended as part of a breastfeeding diet.

What should expectant mothers with post-term pregnancy pay attention to in daily life?

• If there are no signs of labor after 41 weeks of pregnancy, fetal movements should be closely monitored, and prenatal checkups should be conducted as advised by the doctor.
• Expectant mothers should avoid excessive fatigue and be prepared to go to the hospital for delivery at any time.
• The father should stay with the mother, avoid traveling far, and prepare necessary documents and a hospital bag for immediate use when needed.

PREVENTION

Can Postterm Pregnancy Be Prevented?

Yes, it can be prevented by choosing labor induction around 41 weeks of pregnancy to avoid postterm pregnancy.

Regular prenatal checkups in the third trimester are the best way to prevent postterm pregnancy.