Table 1

Descriptive data of primiparous women with singleton births in the period 1992–2010

Characteristics<17 years (n=2392)17–19 years (n=29 816)20–24 years (n=185 942)25–29 years (n=300 822)30–34 years (n=205 905)35–39 years (n=63 163)40+ years (n=10 634)
BMI (kg/m2)22.83.723.24.123.84.323.74.023.84.024.44.124.74.3
BMI* class (kg/m2)
 <18.51355.6%18156.1%76504.1%75092.5%38471.9%9181.5%1331.3%
 18.5–24.9135256.5%16 82356.4%104 60056.3%180 16359.9%122 57159.5%34 43954.5%538150.1%
 25.0–29.931513.2%468715.7%33 96118.3%53 89617.9%37 23418.1%13 31021.1%244223.0%
 30.0–34.9813.4%13274.5%10 5505.7%14 4014.8%93894.6%35755.7%6836.4%
 35–39.9110.5%3371.1%30131.6%40701.4%27241.3%10241.6%1881.8%
 ≥40.040.2%870.3%9040.5%13120.4%9440.5%3420.5%680.6%
 Missing data49420.7%474015.9%25 26413.6%39 47113.1%29 19614.2%955515.1%173916.4%
Smoking*
 Yes66627.8%901230.2%31 67517.0%24 6768.2%13 9716.8%52878.4%9589.0%
 No154264.5%19 15464.3%145 69578.4%261 34886.9%178 79286.8%53 41684.6%888383.5%
 Missing data1847.7%16505.5%85724.6%14 7984.9%13 1426.4%44607.0%7937.5%
Gestational age
 Information available236899.0%29 71599.7%185 70099.9%300 60399.9%205 71999.9%63 09899.9%10 62099.9%
 Missing data241.0%1010.3%2420.1%2190.1%1860.1%650.1%140.1%
  • Figures denote mean and SD or counts and proportions.

  • *Reported height, weight and smoking habits at first antenatal visit.

  • BMI, body mass index.