Table 1. Baseline characteristics for the two study groups.
| Dutch study group | Texan study group | |||||
| Characteristics | NTD children | Control children | NTD children | Control children | ||
| (n = 48) | (n = 62) | P-value | (n = 40) | (n = 79) | P-value | |
| Maternal | ||||||
| Age at delivery (y)* | 30.5 (3.9) | 31.5 (3.3) | NS | 24.8 (6.0) | 24.8 (6.1) | NS |
| BMI (kg/m2)† | 25.4 (7.5) | 23.0 (4.2) | 0.011 | 26.5 (8.1) | 24.7 (7.4) | 0.035 |
| Education: high, n (%) | 6 (12.8) | 20 (33.3) | 0.021 | – | – | – |
| Education (years of school)† | – | – | – | 11 (5) | 12 (4) | NS |
| Periconceptional folic acid supplement use:yes, n (%) | 31 (66.0) | 38 (63.3) | NS | 3 (7.5) | 2 (2.6) | NS |
| Periconceptional smoking: yes, n (%) | 12 (25.5) | 15 (25.0) | NS | 9 (22.5) | 10 (12.8) | NS |
| tHcy, plasma (µmol/L)† | 10.6 (3.3) | 11.1 (4.7) | NS | – | – | – |
| Folate, serum (nmol/L)† | 16.3 (15.9) | 13.4 (13.2) | NS | 25.4 (23.6) | 22.9 (31.3) | NS |
| Folate, RBC (nmol/L)† | 780 (665) | 595 (552) | NS | 738 (616) | 824 (555) | NS |
| Vitamin B12, serum (pmol/L)† | 227 (152) | 313 (184) | 0.007 | 323 (140) | 387 (162) | NS |
| Child | ||||||
| Age at the study moment (y)† | 1.7 (1.5) | 1.2 (0.3) | <0.001 | – | – | – |
| Male sex, n (%) | 16 (34.0) | 24 (40.0) | NS | – | – | – |
| Birth weight (g)* | 3113 (552) | 3343 (313) | <0.001 | – | – | – |
| Gestational age at birth (weeks)† | 38.9 (2.2) | 40.0 (1.3) | 0.001 | – | – | – |
| tHcy, plasma (µmol/L)† | 6.3 (3.1) | 7.1 (1.3) | NS | – | – | – |
| Folate, RBC (nmol/L)† | 1086 (752) | 1228 (813) | NS | – | – | – |
| Folate, serum (nmol/L)† | 31.5 (28.3) | 31.0 (47.6) | NS | – | – | – |
| Vitamin B12, serum (pmol/L)† | 503 (335) | 471 (282) | NS | – | – | – |
Data is presented of the Dutch study group (n = 110) and the Texan study group (n = 119). Values are presented as * mean (SD) or † median (IQR). Chi-square, t- and Mann-Whitney U tests were used to test differences between NTD and control children.