Into the pool

After combing through more than 4,000 studies, the investigators found 31 that met the criteria for the meta-analysis. Of these, 21 were observational studies that reported effect estimates from dichotomous results. These were pooled using a random effects model. Together, they showed that women with SDB had an increased risk for gestational hypertension/preeclampsia and gestational diabetes. Just 9 of the contributing observational studies adjusted for confounders so that adjusted pooled estimates could be computed, and among these, the higher risks for both conditions were sustained. This is impressive, considering that the studies varied in design. In addition, aside from whether or not adjustments were made for confounding, studies also used different diagnostic methods. Polysomnographic (PSG) criteria were used to identify patients with SDB in some studies, and others relied on symptom-based assessments.

Overall, Pamidi et al found a link between SDB and low-birthweight infants. However, only 3 studies included adjusted odds ratios. Although each of these investigations identified a significant association, the researchers said there were too few to allow pooling of the results.