Table 2.
Maternal folic acid supplementation during pregnancy and offspring head size at 20 weeks of gestation, prenatal head growth and postnatal head growtha
| Head circumference size (SDS) | ||||||
|---|---|---|---|---|---|---|
| Basicb | Adjusted for covariatesc | |||||
| SDSd | Be (95 % CI) | P | SDSd | Be (95 % CI) | P | |
| Head size (intercept (SDS) at 20 weeks gestation) and folic acid supplementation (n = 5832 (99.4 %), 11,323 observations) | ||||||
| No usef | −0.163 | Reference | −0.003 | Reference | ||
| Start > 10 weeks | −0.135 | 0.028 (−0.069; 0.126) | 0.57 | −0.004 | −0.001 (−0.104; 0.101) | 0.98 |
| Start ≤ 10 weeks | −0.075 | 0.088 (0.011; 0.166) | 0.03 | 0.028 | 0.031 (−0.054; 0.115) | 0.48 |
| Preconceptional start | 0.058 | 0.221 (0.147; 0.296) | <0.001 | 0.123 | 0.126 (0.037; 0.215) | <0.01 |
| Head circumference growth (SDS) | ||||||
|---|---|---|---|---|---|---|
| Basicb | Adjusted for covariatesc | |||||
| Bg (95 % CI) | P | Bg (95 % CI)) | P | |||
| Period of head growth and folic acid supplementation | ||||||
| Second and third trimester (n = 5832 (99.4 %), 11,323 observations) | ||||||
| No usef | Reference | Reference | ||||
| Start > 10 weeks | 0.002 (−0.008; 0.012) | 0.72 | 0.001 (−0.009; 0.011) | 0.84 | ||
| Start ≤ 10 weeks | 0.004 (−0.004; 0.012) | 0.31 | 0.002 (−0.007; 0.010) | 0.69 | ||
| Preconceptional start | 0.008 (−0.000; 0.016) | 0.05 | 0.002 (−0.007; 0.012) | 0.65 | ||
| Birth through 6 years (n = 5515 (94.0 %), 29,976 observations) | ||||||
| No usef | Reference | Reference | ||||
| Start > 10 weeks | −0.000 (−0.000; 0.000) | 0.32 | −0.000 (−0.000; 0.000) | 0.26 | ||
| Start ≤ 10 weeks | −0.000 (−0.000; 0.000) | 0.45 | −0.000 (−0.000; 0.000) | 0.39 | ||
| Preconceptional start | −0.000 (−0.000; 0.000) | 0.15 | −0.000 (−0.000; 0.000) | 0.26 | ||
SDS standard deviation score
aGender and gestational age-adjusted foetal and child head circumference standard deviation scores
bModel 1: no adjustments
cModel 2: model 1, additionally adjusted for maternal age, ethnicity, education, income, parity, BMI, psychopathology, smoking and alcohol consumption during pregnancy and the interactions between gestational age and maternal smoking, ethnicity and education
dValues represent offspring head size in SDS at 20 weeks of gestation (intercept) per group of folic acid supplementation
eValues represent Β (95 % CI) for the difference in offspring head size (intercept) for each group of folic acid supplementation compared with the reference group of ‘no use’ from mixed model regression analyses
fReference group of primiparae women who never smoked or drank alcohol during pregnancy, with mean age of 29.8 years and mean BMI of 24.5 at enrolment, Dutch national origin, higher education, family income > € 2000/month and median Global Severity Index score of 0.17 in mid-pregnancy
gValues represent Β (95 % CI) for the interaction between maternal folic acid supplementation and gestational age (in weeks) from mixed model regression analyses, i.e. the difference in offspring head circumference growth (in SDS) per week for each group of folic acid supplementation compared with the reference group of ‘no use’