Table 1.
Maternal baseline characteristics of natural and IVF/ICSI pregnancies of the included population.
| Characteristics |
Natural Pregnancies
(n = 555) |
IVF/ICSI Pregnancies
(n = 505) |
p-Value |
| Age a, mean ± SD | 31.8 ± 4.4 | 33.1 ± 4.3 | 0.000 |
| Ethnicity, n (%) | 0.553 | ||
| Dutch | 424 (80) | 390 (81) | |
| Western, other | 27 (5) | 31 (6) | |
| Non-western | 77 (15) | 63 (13) | |
| Education level, n (%) | 0.042 | ||
| Low | 46 (9) | 25 (5) | |
| Intermediate | 172 (33) | 181 (38) | |
| High | 309 (59) | 274 (57) | |
| BMI b, median (IQR) | 24.5 (22.2–28.5) | 24.4 (21.9–27.7) | 0.007 |
| Nulliparous, n (%) | 131 (25) | 249 (51) | 0.000 |
| Alcohol use, n (%) | 197 (37) | 110 (23) | 0.000 |
| Smoking, n (%) | 86 (16) | 57 (12) | 0.047 |
| Folic acid supplement use, n (%) | 520 (98) | 484 (100) | 0.002 |
| Caffeine use, n (%) | 0.285 | ||
| None | 231 (44) | 225 (46) | |
| Moderate | 223 (42) | 181 (37) | |
| High | 76 (14) | 79 (16) | |
| tHcy e, mean ± SD | 6.5 ± 1.7 | 6.3 ± 1.4 | 0.020 |
| Biomarkers * |
Natural Pregnancies
(n = 411) |
IVF/ICSI Pregnancies
(n = 271) |
p-Value |
| tHcy e, median (IQR) | 6.2 (5.3–7.2) | 6.0 (5.2–6.9) | 0.055 |
| Serum folate c, median (IQR) | 38.9 (31.9–44.7) | 41.0 (34.9–55.5) | 0.002 |
| Vitamin B12 d, median (IQR) | 316.5 (237.8–397.0) | 316.0 (256.0–404.0) | 0.238 |
| Paternal tHcy e, median (IQR) | 11.7 (10.0–13.8) | 11.3 (9.7–13.3) | 0.509 |
| Paternal serum folate c, median (IQR) | 17.5 (13.9–22.1) | 18.9 (15.0–24.2) | 0.005 |
| Paternal vitamin B12 d, median (IQR) | 344.0 (271.0–419.0) | 323.5 (260.0–416.0) | 0.426 |
a years, b kg/m2, c nmol/L, d pmol/L, e µmol/L. * Subgroup from November 2010 to December 2016. Alcohol use, smoking, folic acid supplementation and caffeine use were measured during the periconception period. Parametric data is represented as mean ± SD, whereas non-parametric data is represented as median (IQR). Abbreviations: BMI, body mass index; IUI, intrauterine insemination; IVF, in vitro fertilization; ICSI, intracytoplasmic sperm injection; SD, standard deviation; IQR, interquartile range. p-value < 0.05 represented in bold.