Table 1. Characteristics of the study population.

Maternal characteristics	%	n
Age at delivery (N=2,688)
15–19 years	2.0	55
20–24 years	10.9	292
25–29 years	25.8	694
30–34 years	35.3	949
35–39 years	20.5	551
40+ years	5.5	147
Gravidity (N=2,678)
1	30.6	820
2	30.7	822
3	19.0	510
4+	19.6	526
Parity (N=2,678)
0	46.5	1,246
1	32.7	876
2	14.4	386
3	4.3	116
4+	2.0	54
Maternal habits
Smoking (N=2,575)	10.7	276
Alcohol (N=2,569)	2.3	60
Drugs (N=2,571)	2.5	65
≥1 habit (N=2,688)	12.1	324