Fetal Growth and Adipose Fat Tissue Trajectories in Twin Pregnancies after Gastric Bypass Surgery.

Introduction: Previous studies demonstrated a continuous decline in fetal growth throughout singleton pregnancy after bariatric surgery. However, intrauterine growth in twin pregnancy is subjected to further underlying processes. This study was to investigate the longitudinal assessment of fetal biometry and abdominal fat thickness of twin pregnancies conceived after gastric bypass (GB) surgery and compare them to body mass index-matched (BMIM) and obese (OB) controls.

Materials And Methods: We retrospectively assessed ultrasound data of 30 women with dichorionic-diamniotic twin pregnancy (11 women after GB surgery, 9 OB mothers with pregestational BMI ≥30 kg/m2, and 10 BMIM and age-matched controls). We assessed fetal growth parameters including fetal subcutaneous adipose tissue thickness (FSCTT) as well as newborn biometry after delivery. Patient characteristics were obtained from the medical records.

Results: The rise in FSCTT curves was markedly slower in the twin offspring of women with history of GB as compared to the offspring of OB mothers and offspring of BMIM controls. Hence, FSCTT was significantly decreased in the GB offspring as compared to both control groups at 34 weeks of gestation. Also, growth curves of abdominal circumference were decreased in the offspring of GB patients as compared to OB mothers. Infants of mothers with history of GB showed significantly lower birth weight percentiles compared to newborns of OB mothers (27.2 vs. 48.8 pct, p = 0.025). There was no significant difference in inter-twin birth weight difference between the offspring of GB (median: 9.9%, interquartile ranges [IQR]: 6.5-20.0) versus OB (median: 14.6%, IQR: 8.2-21.6) and BMIM controls (median: 9.0%, IQR: 6.3-12.6, p = 0.714).

Conclusions: In summary, intrauterine growth delay in twin pregnancies after GB is assumed to be a multifactorial event with altered metabolism as the most important factor. However, special attention must be paid to the particularity of twin pregnancies as they seem to be subject to other additional mechanism.