ABSTRACT
INTRODUCTION: Maternal underweight (BMI < 18.5) is an uncommon situation with potentially serious obstetric consequences, though data in the literature are scarce. OBJECTIVE: To compare the obstetrical prognosis of patients with normal BMI and BMI < 18.5. STUDY DESIGN: We performed a retrospective study in France (Normandy). RESULTS: We included 14,246 patients between January 2011 and November 2017, among whom 12,648 (88.8 %) had normal BMI, 1269 were considered mild underweight (17 ≤ BMI < 18.5 kg/m²) and 329 (2.3 %) were considered severe to moderate underweight (BMI < 17 kg/m²). The risk of preterm birth was all the greater as the thinness was severe (ORa: 1.34 [1.12-1.60] and ORa 1.77 [1.31-2.34]) and the risk of intrauterine growth retardation also increased with severe thinness (ORa: 1.63 [1.35-1.96] and ORa 2.28 [1.69-3.07]). The risk of a caesarean section or scheduled labour was no different. Neonatal parameters were comparable between the groups. CONCLUSION: Our study confirms an increased risk of preterm delivery and intrauterine growth retardation with increased thinness after adjusting for confounding factors. This link had only been shown previously in 2 studies Neither the type of prematurity (induced or spontaneous) nor the severity of prematurity is influenced by the severity of thinness; however, the low prevalence of thinness limits the power of these data. It would be interesting to study the medico-economic relevance of a policy of close maternal-foetal surveillance in this target population.
