Table 2.
Characteristics of participating mother-child dyads in the two study arms
| Maternal characteristics | Chromosomal testing arm, n=543 | No chromosomal testing arm, n=401 | Difference between groups* |
| Mean (SD) or n (%) | Mean (SD) or n (%) | P value | |
| Age at delivery, years, mean (SD) | 35.5 (5.4) | 33.8 (4.2) | <0.001 |
| Early-pregnancy BMI, mean (SD) | 24.6 (4.6) | 23.5 (3.8) | <0.001 |
| Primiparous, n (%) | 221 (40.7%) | 243 (60.6%) | <0.001 |
| Caesarean section, n (%) | 120 (22.1%) | 79 (19.7%) | 0.37 |
| Hypertension in pregnancy, n (%) | 46 (8.5%) | 20 (5.0%) | 0.38 |
| Gestational diabetes, n (%) | 113 (20.8%) | 78 (19.5%) | 0.61 |
| Smoking during pregnancy, n (%)† | 56 (10.4%) | 14 (3.5%) | <0.001 |
| Antenatal corticosteroid treatment, n (%) | 23 (4.2%) | 9 (2.2%) | 0.95 |
| Child characteristics | |||
| Sex, girl, n (%) | 256 (47.1%) | 204 (50.9%) | 0.26 |
| Preterm birth (<37 weeks), n (%) | 33 (6.1%) | 13 (3.2%) | 0.05 |
| Birth weight, g, mean (SD) | 3482 (580) | 3531 (479) | 0.15 |
% is the proportion of women/children within the sample.
n is the number of participants.
*P values were calculated using Pearson Χ2 tests for categorical variables and using t-tests (equal variances not assumed) for continuous variables.
†Three women in the ITU chromosomal testing arm did not have data on smoking during pregnancy; otherwise, all data presented in this table were complete (available for all participants).
BMI, body mass index; ITU, InTraUterine sampling in early pregnancy.