Several interventions have been proposed to interdict fetal overgrowth. Some include prophylactic labor induction for poorly deined indications such as "impending macrosomia," or elective cesarean delivery to avoid diicult delivery and shoulder dystocia. For women with diabetes in pregnancy, insulin therapy and close attention to good glycemic control reduces birthweight. However, this has not consistently translated into reduced cesarean delivery rates. Furthermore, as noted above, erroneous diagnosis of fetal overgrowth among women with diabetes raises cesarean delivery rates (Scifres, 2015). Also previously mentioned, fetal overgrowth irrespective of the diagnosis of diabetes mellitus is strongly associated with maternal obesity and excessive gestational weight gain (Durie, 2011; Durst, 2016; Harper, 2015). Dietary intervention to limit fetal overgrowth by curbing gestational weight gain, for example, is an active area of research. Currently recommended weight gains for pregnancy according to maternal BMI are described in Chapter 9 (p. 165).
Some clinicians induce labor when fetal macrosomia is suspected in nondiabetic women. his approach is suggested to obviate further fetal growth and thereby reduce potential delivery complications. Such prophylactic induction should theoretically reduce the risk of shoulder dystocia and cesarean delivery. In one systematic review of 11 studies of expectant management versus labor induction for suspected macrosomia, labor induction increased cesarean delivery rates without improving perinatal outcomes (Sanchez-Ramos, 2002). In contrast, Magro-Malosso and colleagues (2017) performed a metaanalysis of four randomized trials involving 1r190 women and concluded that labor induction at 38 or more weeks for suspected macrosomia significantly reduces the frequency of fetal overgrowth and fractures. In one of these studies, 822 women with suspected LGA fetuses were randomly assigned either to early term delivery (37°/7 to weeks) or to expectant management (Boulvain, 2015). here was a higher rate of vaginal delivery that was marginally significant and a lower composite measure of morbidity. These authors cautioned that any beneits should be balanced with the risks of earlyterm labor induction and delivery. Namely, a review of earlyterm births indicates that elective delivery before 39 weeks' gestation does not improve maternal outcomes and is associated with worse neonatal outcomes (Tita, 2016). We agree with the American College of Obstetricians and Gynecologists (2016a, 2017a,b) that current evidence does not support a policy for early labor induction or delivery before 39 weeks' gestation. It remains unclear whether delivery or induction for suspected macrosomia at term is better than expectan t management.
With the delivery of macrosomic infants, shoulder dystocia and its attendant risks described in Chapter 27 (p. 520) are major concerns. That said, the American College of Obstetricians and Gynecologists (20 17b) concluded that fewer than 10 percent of all shoulder dystocia cases result in a persistent brachial plexus injury, and 4 percent of these injuries still follow cesarean delivery.
For prevention, planned cesarean delivery on the basis of suspected macrosomia to prevent brachial plexopathy is an unreasonable strategy in the general population (Chauhan, 2005). Ecker and coworkers (1997) analyzed 80 cases of brachial plexus injury in 77,616 consecutive infants born at Brigham and Women's Hospital. They concluded that an excessive number of otherwise unnecessary cesarean deliveries would be needed to prevent a single brachial plexus injury in neonates born to women without diabetes. Rouse and colleagues (1996) echoed these sentiments in their analysis of nondiabetic mothers.