Residential traffic exposure and pregnancy-related outcomes: a prospective birth cohort study

Table 1 Baseline characteristics (N = 7,339).

Maternal characteristics
Age at intake (yr)	30.5 (20.5-38.0)
Weight at intake (kg)	67.0 (52.0-94.0)
Height (cm)	167.2 (7.4)
Body mass index at intake (kg/m²)	23.8 (19.3-33.5)
Ethnicity
Dutch - Caucasian (%)	54.1
Turkish (%)	8.3
Moroccan (%)	6.4
Surinamese (%)	8.2
Other (%)	15.6
Missing (%)	7.4
Educational level
No education/primary (%)	10.2
Secondary (%)	39.9
Higher (%)	40.9
Missing (%)	9.0
Parity
Nulliparous (%)	55.0
Multiparous (%)	43.8
Missing (%)	1.2
Smoking in pregnancy
No (%)	72.1
Yes (%)	15.5
Missing (%)	12.4
Alcohol consumption in pregnancy
No (%)	52.7
Yes (%)	36.5
Missing (%)	10.8
Birth and pregnancy outcomes
Gestational age at birth (wk)	40.1 (36.9-42.1)
Birth weight (g)	3417.6 (561.0)
SDS birth weight	-0.10 (1.03)
Male (%)	50.3
Small size for gestational age at birth (<-2.0 SDS) (%)	3.5
Preterm birth (<37 wk) (%)	5.5
Pregnancy-induced hypertension (%)	3.4
(Pre)eclampsia or HELLP (%)	2.0
Gestational diabetes (%)	0.7

Values are means (SDS) or medians (90% range) for variables with a skewed distribution, and percentages in case of categorical variables.
Of the total group, data were missing on maternal weight at intake (n = 31), maternal height at intake (n = 26), BMI at intake (n = 56), gestational age at birth (n = 2), fetal sex (n = 29), birth weight (n = 51), SDS birth weight (n = 61), SGA at birth (n = 61), preterm birth (n = 2), pregnancy-induced hypertension (n = 231), (pre)eclampsia/HELLP (n = 231), and gestational diabetes (n = 271).

ISSN: 1476-069X