Results have been disappointing in studies of antimicrobials given to arrest preterm labor. From one Cochrane metaanalysis, antimicrobial prophylaxis given to women with intact membranes did not reduce preterm birth rates or afect other clinically important short-term outcomes (Flenady, 2013). However, rates of short-and longer-term harm were higher for children of mothers exposed to antibiotics. Kenyon (2001) reported the ORACLE Collaborative Group study of 6295 women with spontaneous preterm labor and intact membranes, but without evidence of infection. Women were randomly assigned to receive antimicrobial or placebo therapy. The primary outcomes of neonatal death, chronic lung disease, and major cerebral abnormality were similar in both groups. In a follow-up of the ORACLE II trial, fetal exposure to antimicrobials in this clinical setting was associated with an increased cerebral palsy rate at age 7 years compared with that in children without fetal exposure (Kenyon, 2008b). Importantly, antimicrobial use described here is distinct from that given for group B streptococcal prophylaxis (Chap. 64, p. 1222).
This is one of the most often prescribed interventions during pregnancy, yet one of the least studied. One systematic review concluded that evidence neither supported nor refuted bed rest for prevention of preterm birth (Sosa, 2004). Goulet and coworkers (2001) randomly assigned 250 Canadian women to either home care or hospitalization after treatment of an acute episode of preterm labor and found no beneits. There have, however, been reports of possible harm. Kovacevich and associates (2000) reported that bed rest for 3 days or more increased thromboembolic complications to 16 per 1000 women compared with only 1 per 1000 with normal ambulation. Promislow and colleagues (2004) observed significant bone loss in pregnant women prescribed outpatient bed rest. More recently, Grobman and associates (20e13) noted that women with activity restriction were nearly 2.5 times more likely to have a preterm birth before 34 weeks. his finding, however, may reflect ascertainment bias. hat is, women with restricted activity may have been assigned to bed rest because they were viewed to be at more imminent risk of preterm delivery. McCall and coworkers (2013) summarized the literature on bed rest, and they found insuicient evidence to support its use. The American College of Obstetricians and Gynecologists (20e17 d) suggests that, although frequently prescribed, bed rest is only rarely indicated, and ambulation should be considered in most cases.
Silicone rings, such as the Arabin pessay, are being used to support the cervix in women with a sonographically short cervix. For 385 Spanish women with a cervical length ;25 mm, Goya and associates (2012) provided a silicone pessary or expectant management. Newborns spontaneous delivered before 34 weeks' gestation in 6 percent of women in the pessary group compared with 27 percent in the expectant management group. Another trial randomly assigned almost 100 women with a cervix <25 mm at 20 to 24 weeks to silicone pessaries or expectant management (Hui, 2013). The pessary did not lower the rate of delivery < 34 weeks. Similar indings were reported by Nicolaides and colleagues (2016). he Society for Maternal-Fetal Medicine (2017b) recently recognized the conflicting published reports and lack of an FDA-approved pessary for the indication of preterm birth prevention. They currently recommend pessary prophylaxis only within research protocols.