Postterm Birth

If you thought all it took to deliver a prolonged pregnancy is having a C/S, here's a good review of all the factors that need to be considered before a postterm birth:

What distinguishes a good perinatal outcome from a tragic one like stillbirth? It has a lot to do with the timely onset of labor and delivery. In fact, both preterm birth (delivery before 37 weeks of gestation) and postterm birth have been linked to elevated neonatal morbidity and mortality. For prolonged births, for example, the risk of stillbirth plus early neonatal deaths doubles by 42 weeks of gestation and rises fourfold by 43 weeks (compared to the risk at term). And this is by conservative estimates.

The article's take-home message:

An accurate assessment of gestational age is critical for diagnosing prolonged pregnancy (gestation longer than 42 and 0/7 weeks or 294 days). With the possible exception of ART [assisted reproductive technology], ultrasound exam in the first and early midtrimester is the most accurate technique of dating a pregnancy.

Commonly overlooked, maternal risks of prolonged pregnancy include labor dystocia, cesarean delivery, and severe perineal injury.

We recommend routine induction of labor in low-risk singleton pregnancies at 41 weeks' gestation, regardless of cervical exam results. If unfavorable, cervical ripening with prostaglandin agents may be necessary, unless contraindicated.

If elective induction of labor at 41 weeks fails, it's reasonable to stop the induction, send the patient home, and try again at 42 weeks' gestation, so long as fetal testing has been reassuring and the fetal membranes are intact.

Fetal dysmaturity (postmaturity) syndrome (a term now used to describe infants with intrauterine growth restriction resulting from chronic uteroplacental insufficiency) complicates 20% of postterm pregnancies.

Never forget that, unlike preterm labor and birth, the risks associated with prolonged pregnancy can be almost entirely prevented by timely delivery.