A Cochrane review included 17 trials involving 12 264 women. The trials were generally of good to excellent quality, although three used an allocation method likely to introduce bias. Programs offering additional social support for at-risk pregnant women were not associated with improvements in any perinatal outcomes: the numbers of preterm babies (RR 0.92, 95% CI 0.83 to 1.01; 11 studies, n= 10 429; low birthweight babies (RR 0.92, 95% CI 0.83 to 1.03; 11 studies, n = 8 681), or perinatal mortality (RR 0.96, 95% CI 0.74 to 1.26; 11 studies, n = 7 522, but there was a reduction in the likelihood of antenatal hospital admission (RR 0.79, 95% CI 0.68 to 0.92; 3 studies, n=737) and caesarean birth (RR 0.87, 95% CI 0.78 to 0.97; 9 studies, n=4 522). Women who received additional social support were more likely to have their pregnancies terminated (RR 2.87, 95% CI 1.42 to 5.78; 5 studies, n= 5 587).
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison).