Epidemiological evidence that severe obese women (pre-pregnancy BMI ≥40 kg/m²) should lose weight during their pregnancy

Abstract

Objectives

Defining the optimal gestational weight gain (optGWG) allowing to have “normal shaped” babies (10% of Small for gestational age, SGA, and10% of large LGA babies) in severe obese women (pre-pregnancy BMI ≥40 kg/m²).

Study design

South-Reunion University’s maternity (Reunion Island, Indian Ocean). 20 year-observational cohort study (2001–2019). Epidemiological perinatal data base with information on obstetrical and neonatal risk factors. All consecutive term (37–42 weeks gestation) singleton pregnancies (>21 weeks) live birth pregnancies delivered in the maternity.

Main outcome measures

OptGWG to obtain newborns as close as possible of the 10% SGA/LGA goal for each BMI categories, 15–19.9, 20–24.9 …, as well as severe obese ≥40 kg/m².

Results

Of the 71,318 singleton term live births (37 weeks onward), we could define the maternal pre-pregnancy body mass index and the GWG in of 61,764 patients (86.6%). Severe obese 40 kg/m² losing 5–9.9 kg have 12.9% of LGA and 11.9% of SGA babies. Those losing 10 kg and more 12.7% of LGA and 7.3% of SGA. Our formerly proposed linear equation (validated from 15 to 40 kg/m²) may be prolonged at 45 kg/m².   $$\text{opGWG}\left(\text{kg}\right)=-1.2\text{pp BMI}\left(\text{Kg}/{\mathrm{m}}^2\right)+42\pm 2\text{kg}$$

Conclusion

In our population, a 32 kg/m² obese should gain 3.6 kg (instead of 5–9 kg, IOM 2009). A very obese 40 kg/m² should lose 6 kg, and a severe obese 45 kg/m² lose 12 kg.

Keywords:

• Pregnancy
• epidemiology
• pre-pregnancy body mass index
• gestational weight gain
• cesarean section
• obesity
• preeclampsia

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

No specific fundings besides the French government funding for the South-Reunion perinatal database.