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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Diabetes In Pregnancy Series
Sponsored by The Indian Health Service Clinical Support Center
PART 2: Management, delivery, and postpartum
8. Labor and Delivery
Case continued
Ms Kanulie has an ultrasound done at 38 weeks gestation that reports an estimated fetal weight of 4086 g (>90th percentile for this gestational age). The AFI at this exam is 20.7. Her fundal height is 41 cm. Her total weight gain has been 12 pounds. Her blood pressure is normal. She reports good fetal movements and her NST are consistently reactive. Her glucose control remains satisfactory with most values in range on 28 units of NPH and 12 units before breakfast and 18 units of NPH and 12 units of regular before supper. Vaginal exam reveals that her cervix is 2 cm dilated, 50% effaced, soft, posterior, with a vertex presentation at –3 station. She wants to know if she could be delivered before the baby gets any bigger.
Labor and Delivery
There is some evidence that inducing labor in insulin-dependent diabetics at 38-39 weeks may decrease the incidence of macrosomic infants and shoulder dystocia, and, in women with a prior stillbirth, such as our patient, many experts would recommend this policy.
Conway et al found that an ultrasonographically estimated weight threshold as an indication for elective delivery in diabetic women reduces the rate of shoulder dystocia without a clinically meaningful increase in cesarean section rate. Lurie et al found that the incidence of shoulder dystocia in patients in whom labor was electively induced at 38 to 39 weeks of gestation was 1.4% as compared to 10.2% in patients who delivered beyond 40 weeks' gestation (p < 0.05).
The ADA suggests that prolongation of gestation beyond 38 weeks may increase the risk of fetal macrosomia without reducing the cesarean delivery rates, so that delivery during the 38th week is recommended unless obstetric considerations dictate otherwise. Kjos et al 1993 concluded that in women with uncomplicated insulin-requiring gestational or class B pregestational diabetes, expectant management of pregnancy after 38 weeks' gestation did not reduce the incidence of cesarean delivery. Moreover, there was an increased prevalence of large-for-gestational-age infants (23% vs 10%) and shoulder dystocia (3% vs 0%). Because of these risks, delivery should be contemplated at 38 weeks and, if not pursued, careful monitoring of fetal growth must be performed.
On the other hand, the Cochrane Library points here is very little evidence to support either elective delivery or expectant management at term in pregnant women with insulin-requiring diabetes. Limited data from a single randomized controlled trial suggest that induction of labour in women with gestational diabetes treated with insulin reduces the risk of macrosomia. The small sample size does not permit one to draw conclusions.
At this gestational age, amniocentesis for confirmation of fetal lung maturity is not necessary in well-dated, well-controlled patients. One should anticipate that the cesarean delivery rate will be higher in women who are induced with an unfavorable cervix, but our patient is a multipara with an inducible cervix. We should of course like to avoid another shoulder dystocia and the poor outcome that occurred during her previous pregnancy.
Ultrasound is not a very good predictor of fetal macrosomia, having a positive predictive value of only 20 to 40%, comparable to Leopold’s maneuvers. Its negative predictive value is much better however, over 90%, but it is always best to put the whole clinical picture together.
Elective cesarean delivery for suspected macrosomia is not a reasonable strategy, as over 400 cesareans would have to be performed in women with GDM to prevent one shoulder dystocia with sequelae.
Naylor et al reported that the mere presence of the diagnosis of GDM may lead to increased rates of cesarean delivery, without regard to a specific indication, nor improvement in maternal or infant outcome.
On the other hand, if a prolonged second stage with arrest of descent of the head occurs, it would be most imprudent to attempt a forceps or vacuum assisted vaginal delivery of a fetus suspected to weigh over 4000 g.
ACOG states for women with GDM and an estimated fetal weight of 4,500 g or more, cesarean delivery may be considered because it may reduce the likelihood of permanent brachial plexus injury in the infant.
There is evidence that maintaining maternal euglycemia in labor is effective in preventing neonatal hypoglycemia, actually more so than total antepartum control. (Curet et al, Anderson et al) Thus continuing insulin therapy intrapartum with close monitoring is indicated. Here is a set of intrapartum insulin drip orders we use.
