title: Higher maternal leptin levels at second trimester are associated with subsequent greater gestational weight gain in late pregnancy.
abstract: BACKGROUND
  Excessive gestational weight gain (GWG) is associated with adverse pregnancy outcomes. In non-pregnant populations, low leptin levels stimulate positive energy balance. In pregnancy, both the placenta and adipose tissue contribute to circulating leptin levels. We tested whether maternal leptin levels are associated with subsequent GWG and whether this association varies depending on stage of pregnancy and on maternal body mass index (BMI).
  
  
  METHODS
  This prospective cohort study included 675 pregnant women followed from 1(st) trimester until delivery. We collected anthropometric measurements, blood samples at 1(st) and 2(nd) trimester, and clinical data until delivery. Maternal leptin was measured by ELISA (Luminex technology). We classified women by BMI measured at 1(st) trimester: BMI < 25 kg/m(2) = normal weight; 25 ≤ BMI < 30 kg/m(2) = overweight; and BMI ≥ 30 kg/m(2) = obese.
  
  
  RESULTS
  Women gained a mean of 6.7 ± 3.0 kg between 1(st) and 2(nd) trimester (mid pregnancy GWG) and 5.6 ± 2.5 kg between 2(nd) and the end of 3(rd) trimester (late pregnancy GWG). Higher 1(st) trimester leptin levels were associated with lower mid pregnancy GWG, but the association was no longer significant after adjusting for % body fat (%BF; β = 0.38 kg per log-leptin; SE = 0.52; P = 0.46). Higher 2(nd) trimester leptin levels were associated with greater late pregnancy GWG and this association remained significant after adjustment for BMI (β = 2.35; SE = 0.41; P < 0.0001) or %BF (β = 2.01; SE = 0.42; P < 0.0001). In BMI stratified analyses, higher 2(nd) trimester leptin levels were associated with greater late pregnancy GWG in normal weight women (β = 1.33; SE = 0.42; P =0.002), and this association was stronger in overweight women (β = 2.85; SE = 0.94; P = 0.003--P for interaction = 0.05).
  
  
  CONCLUSIONS
  Our results suggest that leptin may regulate weight gain differentially at 1(st) versus 2(nd) trimester of pregnancy: at 2(nd) trimester, higher leptin levels were associated with greater subsequent weight gain--the opposite of its physiologic regulation in non-pregnancy--and this association was stronger in overweight women. We suspect the existence of a feed-forward signal from leptin in second half of pregnancy, stimulating a positive energy balance and leading to greater weight gain.
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.
authors.forename: Marilyn
authors.initials: M
authors.lastname: Lacroix
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Battista
authors.affiliation: Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada.
authors.forename: Myriam
authors.initials: M
authors.lastname: Doyon
authors.affiliation: Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Moreau
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Patenaude
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Guillemette
authors.affiliation: Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Ménard
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.|Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Ardilouze
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada.|Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada.
authors.forename: Patrice
authors.initials: P
authors.lastname: Perron
authors.affiliation: Department of Medicine, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec, Canada. marie-france_hivert@harvardpilgrim.org.|Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue North, wing 9, door 6, Sherbrooke, Québec, Canada. marie-france_hivert@harvardpilgrim.org.|Diabetes Center, Massachusetts General Hospital, 50 Staniford Street, Boston, MA, USA. marie-france_hivert@harvardpilgrim.org.|Department of Population Medicine, Harvard Medical School, Harvard Pilgrim Health Care Institute, 401 Park Drive, suite 401, Boston, MA, USA. marie-france_hivert@harvardpilgrim.org.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Hivert
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D050177:Overweight / Q000097:blood; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood; D011261:Pregnancy Trimester, First / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood*; D011446:Prospective Studies; D012307:Risk Factors; D015430:Weight Gain / Q000502:physiology*
chemical_list: D020738:Leptin
keywords: Body mass index; Leptin; Pregnancy; Weight gain