TABLE 1

Descriptive Characteristics of the 2000–2001 UBCS and 2012–2013 SPATZ Birth Cohorts

Descriptive Characteristic2000–2001 UBCS, % (n = 989)2012–2013 SPATZ, % (n = 856)P
Education ≥12 y37.760.9<.001a
Alcohol consumed in year before pregnancy67.869.5.446
Alcohol consumption during lactationNA
 Never drinkerNA23.1
 Abstinent drinkerNA26.0
 Resumed at 6 wk to 6 moNA20.5
 Resumed by 6 wkNA19.9
 Undetermined drinkingNA10.5
Smoked in year before pregnancy32.527.1.012a
Smoking during lactation<.001a
 Never smoker66.471.5
 Abstinent smoker11.710.6
 Resumed smoking2.43.4
 Continuous smoker13.46.1
 Undetermined smoker6.08.4
Prepregnancy BMI.004a
 Normal (≤18.5 to <25)66.761.4
 Underweight (<18.5)3.42.2
 Overweight (≤25 to 30)21.423.4
 Obese (≥30)8.513.0
Delivery mode<.001a
 Vaginal spontaneous80.067.1
 Elective cesarean5.012.1
 Emergency cesarean10.912.3
 Vaginal assisted4.18.5
Age at delivery, y<.001a
 <3037.826.6
 30–3539.343.0
 >3523.030.4
Returned to work after deliveryNA
 NoNA63.7
 Month 1–3NA5.3
 Month 4–6NA4.4
 Month 7–12NA8.3
 UndeterminedNA18.3
German nationality79.885.2.002a
Parity ≥1 birth49.748.1.490
Initiation of predominant breastfeeding85.285.6.829
Predominant breastfeeding at 4 mob65.564.5.689
Initiation of any breastfeeding91.694.7.012a
Any breastfeeding at 6 moc58.667.2<.001a
  • NA, not available.

  • a Significant P value.

  • b Restricted to subjects with noncensored data on predominant breastfeeding at 4-month data (UBCS n = 829; SPATZ n = 673).

  • c Restricted to subjects with noncensored data on any breastfeeding at 6-month data (UBCS n = 863; SPATZ n = 714).