TABLE 1

Baseline characteristics of study population by total duration of lactation. Data from 570 participants in Project Viva who presented for follow-up at 3 years postpartum without an intervening birth

Months of lactationP*
None>0 to <33 to <66 to <12≥12
n = 70n = 92n = 117n = 141n = 150
Mean(SD)Mean(SD)Mean(SD)Mean(SD)Mean(SD)
Prepregnancy BMI (kg/m2)26.8(6.0)26.9(7.3)24.9(5.0)24.8(5.2)23.7(3.8)<0.001
Gestational weight gain (kg)15.1(6.7)14.6(6.2)15.7(5.5)14.5(5.2)14.9(5.0)0.54
Postpartum weight retention at 3 years (kg)3.7(7.5)1.8(10.0)2.9(5.7)2.4(5.6)1.8(5.7)0.28
Age at 3-year visit36.0(4.8)36.8(6.0)37.2(5.3)38.2(4.6)38.8(5.0)<0.001
n(%)n(%)n(%)n(%)n(%)
Race0.10
 Asian0(0)5(5)7(6)5(4)5(3)
 Black12(17)16(17)21(18)13(9)19(13)
 Hispanic2(3)9(10)11(9)8(6)7(5)
 Other3(4)4(4)8(7)3(2)6(4)
 White53(76)58(63)70(60)112(79)113(75)
Parity0.006
 112(17)39(42)37(32)33(23)41(27)
 236(51)40(44)57(49)73(52)64(43)
 ≥322(31)13(14)23(20)35(25)45(30)
Gestational glucose tolerance0.74
 Gestational diabetes3(4)6(7)4(3)4(3)5(3)
 Impaired glucose tolerance3(4)2(2)8(7)5(4)6(4)
 Transient hyperglycemia5(7)12(13)13(11)14(10)11(7)
 Normal59(84)72(78)92(79)118(84)128(85)
Parental history of diabetes0.85
 Yes11(16)17(19)19(16)20(14)20(13)
 No59(84)75(82)98(84)121(86)130(87)
Hormonal contraception0.04
 Yes4(10)16(28)7(10)17(21)16(15)
 No37(90)42(72)64(90)65(79)92(85)
Current smoker<0.001
 Yes8(11)13(14)7(6)7(5)3(2)
 No50(71)73(79)104(89)129(91)139(93)
 Missing12(17)6(7)6(5)5(4)8(5)
Plan to exclusively breastfeed at 3 months <0.001
 Yes1(1)12(13)26(22)74(52)100(67)
 No69(99)80(87)91(78)67(48)50(33)
Fasting sample0.34
 Yes16(23)30(33)40(34)38(27)51(34)
 No54(77)62(67)77(66)103(73)99(66)
  • *ANOVA P value for continuous variables, χ2 P value for categorical variables.

  • †Using hormonal contraception at 2–3 years postpartum, as reported at the 6-year follow-up visit. Missing for 210 participants.

  • ‡At the 28-week interview, each participant reported how she intended to breastfeed her infant at 3 months postpartum.