Table 1.

Family characteristics among singletons born at term or preterm (Denmark 2003–2008 (n=1776))

Characteristics	Born at term (≥37 weeks)	Late preterm birth (34 to <37 weeks)	Moderately or very preterm birth (<34 weeks)*
Number of infants (n)	1728	40	8
Maternal age (years, mean (SD))	30.8 (4.4)	30.4 (4.5)	28.8 (3.4)
Maternal prepregnancy BMI (kg/m2, median (10/90 percentile))†	22.6 (19.6/28.7)	22.7 (18.4/33.0)	22.8 (16.5/28.2)
Maternal smoking in pregnancy (%)	31.7	30.0	37.5
Maternal alcohol consumption in pregnancy (%)‡
0 drinks/week	47.6	55.0	50.0
1–4 drinks/week	41.3	37.5	37.5
5+ drinks/week§	11.1	7.5	12.5
Maternal marital status (%)¶
Single**	12.4	10.3	25.0
Cohabitating	87.6	89.7	75.0
Maternal IQ (mean (SD))††	100.0 (14.9)	97.7 (16.9)	104.3 (17.9)
Parental educational level (years, mean (SD))‡‡	13.2 (1.9)	13.0 (1.6)	14.2 (1.8)
Parity (%)
0	50.7	60.0	87.5
1	32.1	30.0	12.5
2+	17.2	10.0	0.0
Child sex (%)
Males	51.7	60.0	50.0
Females	48.3	40.0	50.0
Gestational age (days, median (10/90 percentile))	282.0 (269.0/293.0)	251.5 (241.0/257.5)	227.5 (206.0/236.0)
Birth weight (g, mean (SD))§§	3627.3 (483.4)	2740.8 (482.6)	2040.9 (458.4)
Child age at testing (years, median (10/90 percentile))	5.23 (5.12/5.30)	5.26 (5.13/5.31)	5.23 (5.10/5.29)

*Lowest observation 29 weeks.

†Information missing for 35 term and 1 late preterm birth.

‡Information missing for one term birth.

§Range 5–14 drinks/week.

¶Information missing for 13 term and 1 late preterm birth.

**If reported being single either during pregnancy or at follow-up at 60–64 months post partum.

††Information missing for nine term births.

‡‡Information missing for five term and one late preterm birth.

§§Information missing for 12 term and 2 late preterm births.

BMI, body mass index; IQ, intelligence quotient; N, number; SD, standard deviation.