Maternal weight gain in twin-twin transfusion syndrome.

Objective. To examine the association between maternal weight gain and twin–twin transfusion syndrome (TTTS). Design. Retrospective observational study in two tertiary care centers. Population. All 124 women with monochorionic diamniotic twin pregnancies who gave birth at ≥16 gestational weeks between 2002 and 2010. Methods. Analysis of chronological relation between maternal weight gain per week (weekly gain) and the diagnosis of TTTS. Main outcome measure. Sonographic diagnosis of TTTS. Results. A weekly weight gain ≥1.4 kg occurred in 45 women, preceded the diagnosis of TTTS in 22 (78.6%) of the 28 women with TTTS, and was associated with TTTS [women with one weekly weight gain ≥1.4 kg vs. women with no weekly weight gains ≥1.4 kg who were diagnosed as having TTTS: 48.9% (22/45) vs. 7.6% (6/79); RR, 6.44; 95%CI, 2.82–14.69]. At given gestational weeks between 16 and 27, the mean (±SD) prospective risk of the development of TTTS within three weeks was 52.0±33.8% among women who showed a weekly weight gain ≥1.4 kg for the first time, whereas the risk of the development of TTTS within one week was 1.6±1.7% among women who never showed a weekly weight gain ≥1.4 kg. Conclusions. Excessive maternal weight gain ≥1.4 kg/week is likely to occur during the development of TTTS.