Impact of Roux-en-Y gastric bypass and sleeve gastrectomy on fetal growth and relationship with maternal nutritional status

Surg Obes Relat Dis. 2018 Oct;14(10):1488-1494. doi: 10.1016/j.soard.2018.07.014. Epub 2018 Jul 20.


Background: There is a lack of evidence on whether sleeve gastrectomy (SG), which induces fewer nutritional deficiencies than Roux-en-Y gastric bypass (RYGB), also affects fetal growth (FG).

Objectives: To compare neonatal outcomes after RYGB and SG and to assess the impact of maternal nutritional alterations on FG after both procedures.

Setting: University Hospital, France.

Methods: Women with singleton pregnancies who had at least 1 nutritional evaluation in our institution between 2004 and 2017 were included. FG was assessed with birth weight (BW) and BW-Z score (adjusted for sex and term), and maternal nutritional deficiencies were defined according to standard and pregnancy-specific norms.

Results: During the study period 123 pregnancies were included, 77 after RYGB and 46 after SG. Weight loss was higher after RYGB than after SG (45.6 ± 12.4 versus 39.5 ± 13.7 kg, P = .02), but mean weight before pregnancy and weight gain during pregnancy were similar. Mean BW (3026 ± 677 versus 3162 ± 712 g), mean BW Z-score and incidence of small for gestational age (24% versus 19%) were not significantly different after RYGB and SG. Mean number of nutritional deficiencies during the second trimester was similar (2.2 ± 1.5 versus 2.1 ± 1.2 with specific norms), but the affected parameters differed between procedures. Urinary urea (R = .285, P = .04) was positively correlated to BW Z-score after both procedures. In contrast, serum iron parameters were negatively associated to BW Z-score.

Conclusion: FG restriction occurs after both SG and RYGB. FG after bariatric surgery is positively associated with protein supply and negatively correlated with maternal iron status.

Keywords: Bariatric surgery; Fetal growth; Gastric bypass; Nutritional status; Pregnancy; Sleeve gastrectomy.

Publication types

  • Comparative Study
  • Observational Study

MeSH terms

  • Adult
  • Bariatric Surgery / adverse effects*
  • Dietary Supplements
  • Female
  • Fetal Development / physiology*
  • Fetal Macrosomia / etiology
  • Gastrectomy / adverse effects*
  • Gastric Bypass / adverse effects
  • Gestational Weight Gain / physiology
  • Humans
  • Infant, Small for Gestational Age
  • Iron / metabolism
  • Malnutrition / etiology
  • Malnutrition / physiopathology
  • Nutritional Status / physiology
  • Obesity, Morbid / physiopathology
  • Obesity, Morbid / surgery*
  • Postoperative Complications / etiology
  • Postoperative Complications / physiopathology
  • Pregnancy
  • Pregnancy Complications / physiopathology
  • Pregnancy Complications / surgery*
  • Pregnancy Outcome
  • Pregnancy Trimester, First
  • Pregnancy Trimester, Second
  • Prenatal Care
  • Prenatal Nutritional Physiological Phenomena / physiology*
  • Prospective Studies
  • Proteins / metabolism
  • Retrospective Studies
  • Weight Loss / physiology


  • Proteins
  • Iron