Induction of Labor
As a follow up to my last post about advanced maternal age (AMA), I will discuss induction of labor. Women in the AMA age range may be counseled about induction of labor due to the slightly increased risk of stillbirth after the due date or due to complications of pregnancy. Some women may also request induction of labor due to discomfort at the end of pregnancy, or timing concerns relating to delivery.
An induction of labor can happen for a variety of reasons, both medical and social. Here are some indications for induction of labor:
- Advanced maternal age
- Gestational diabetes or pre-pregnancy diabetes
- Hypertension, gestational hypertension (caused by pregnancy), or pre-eclampsia
- Post term pregnancy that goes past 41 weeks
- Vaginal bleeding
- Low amniotic fluid
- Premature rupture of membranes, preterm premature rupture of membranes
- Desire for a scheduled delivery
- History of fast labor, or long distance from hospital
Risks and Benefits
There are risks and benefits to induction of labor. Risks include a longer labor, failure to progress (cervix does not dilate all the way to 10cm in order to start pushing), need for c-section, and fetal distress due to frequent or strong contractions.
The benefit of an induction of labor is that the delivery can be somewhat scheduled, and the baby can be delivered safely before risks of prolonging the pregnancy cause complications for the mother or the baby. The doctor and patient need to weigh the risks and benefits and decide the optimal timing for good outcomes for both the mother and the baby.
Timing of Induction
The estimated date of delivery is considered 40 weeks.
An elective induction of labor (not due to a medical indication) cannot be scheduled before 39 weeks because babies are still developing, and can have complications such as breathing problems even in early term gestational age (after 37 weeks).
A pregnancy should not go past 42 weeks so typically if there are no signs of labor and no pregnancy complications, an induction will be scheduled between 41 and 42 weeks.
Timing of induction for medical complications of pregnancy depend on the severity, and multiple factors relating the the fetal and maternal well being. For example, patients who develop high blood pressure may be delivered between 37-39 weeks, patients diagnosed with pre-eclampsia may be delivered at 37 weeks if mild, but earlier if there are severe features. Patients with diabetes may need to be induced earlier than the due date if blood sugars are not well controlled.
Methods of Induction
Depending on the cervical exam, medications which cause “cervical ripening” may be used to start the induction. Cervical ripening is needed when the cervix is not dilated, is firm rather than soft, and still thick (not effaced).
Examples of cervical ripening medications are Misoprostol (Cytotec) and Cervidil. These medications are placed in the vagina every 4 hours (Misoprostol) or once for 12 hours (Cervidil). After the cervix is more dilated, effaced, and softened, IV pitocin is usually started. This will cause contractions. Sometimes a catheter is placed through the cervix and a balloon on the end is inflated in order to help dilate the cervix in addition to the IV pitocin. Later in the labor process membranes can be ruptured (AKA break water).
An induction of labor typically takes longer than spontaneous labor, and the time it takes for labor to progress depends on the number of deliveries a woman has had previously, and her cervical exam at the start of the induction.
An induction of labor for a woman’s first pregnancy (especially if the cervix is closed at the beginning) can take 24-48 hours, though hopefully less! On the other hand, if a woman has had multiple vaginal deliveries in the past, and her cervix is dilated at the beginning, it may only take a few hours, and typically less than 12.
Contractions that cause a woman’s cervix to dilate are painful whether or not they are caused by an induction medication, or happen naturally. It may be more difficult to go through labor without an epidural for women who have an induction of labor simply because the labor takes longer.
I typically recommend awaiting spontaneous labor when a pregnancy is uncomplicated. However, inductions or interventions to augment labor are often necessary and helpful for optimal outcomes and healthy babies and mothers.
By Loriana Soma, M.D. - Expert OB/GYN