From: Nitrates in drinking water and methemoglobin levels in pregnancy: a longitudinal study
Characteristics | All n = 357 | Private System n = 224 (63%) | Public System n = 133 (37%) | p-valuea |
---|---|---|---|---|
Age at enrollment | 29.4 ± 5.3 | 29.9 ± 5.4 | 28.6 ± 5.2 | 0.03 |
Age groups | Â | Â | Â | 0.04 |
   <20 | 19 (5%) | 11 (5%) | 8 (6%) |  |
   21-29 | 172 (48%) | 99 (44%) | 73 (55%) |  |
   30-35 | 125 (35%) | 86 (38%) | 39 (29%) |  |
   >35 | 41 (12%) | 28 (13%) | 13 (10%) |  |
Highest education group | Â | Â | Â | 0.67 |
   <High School | 15 (4%) | 9 (4%) | 6 (5%) |  |
   ≥High School | 303 (85%) | 196 (88%) | 107 (80%) |  |
   Refused/missing | 39 (11%) | 19 (8%) | 20 (15%) |  |
Race | Â | Â | Â | 0.001 |
   White | 307 (86%) | 203 (91%) | 104 (78%) |  |
   Other | 11 (3%) 2 (1%) 9 (7%) |  | ||
   Refused/missing | 39 (11%) 19 (8%) 20 (15%) |  | ||
Ethnicity | Â | Â | Â | 0.03 |
   Non-Hispanic | 310 (87%) | 203 (91%) | 107 (80%) |  |
   Hispanic | 8 (2%) | 2 (1%) | 6 (5%) |  |
   Refused/missing | 39 (11%) | 19 (8%) | 20 (15%) |  |
Tobacco use at enrollment | Â | Â | Â | 0.47 |
   Never | 216 (60%) | 133 (59%) | 83 (62%) |  |
   Previously | 92 (26%) | 58 (26%) | 34 (26%) |  |
   Present | 49 (14%) | 33 (15%) | 16 (12%) |  |
Alcohol use during pregnancy | Â | Â | Â | 0.03 |
   Yes | 32 (9%) | 18 (8%) | 14 (11%) |  |
   No | 292 (82%) | 192 (86%) | 100 (75%) |  |
   Missing/refused | 33 (9%) | 14 (6%) | 19 (14%) |  |
Weeks gestation at enrollment | Â | Â | Â | 0.19 |
   <8 weeks | 41 (12%) | 21 (9%) | 20 (15%) |  |
   8-10 weeks | 57 (16%) | 34 (15%) | 23 (17%) |  |
   11-13 weeks | 259 (72%) | 169 (76%) | 90 (68%) |  |
Mean gestational age (weeks) | 10.3 ± 1.6 | 10.4 ± 1.5 | 10.0 ± 1.6 | 0.06 |
   Parity |  |  |  | 0.004 |
   0 | 92 (26%) | 48 (22%) | 44 (33%) |  |
   ≥1 | 226 (63%) | 157 (70%) | 69 (52%) |  |
   Refused/missing | 39 (11%) | 19 (8%) | 20 (15%) |  |
Vitamin use at enrollment | Â | Â | Â | 0.21 |
   Yes | 306 (86%) | 196 (87%) | 110 (83%) |  |
   No | 51 (14%) | 28 (13%) | 23 (17%) |  |
Gravidity | Â | Â | Â | 0.01 |
   0 | 92 (26%) | 48 (21%) | 44 (33%) |  |
   1 | 84 (23%) | 56 (25%) | 28 (21%) |  |
   2 | 78 (22%) | 61 (27%) | 17 (13%) |  |
   ≥3 | 74 (21%) | 47 (21%) | 27 (20%) |  |
   Refused/missing | 29 (8%) | 12 (5%) | 17 (13%) |  |
Medication use b | Â | Â | Â | 0.85 |
   Yes | 233 (65%) | 147 (66%) | 86 (65%) |  |
   No | 124 (35%) | 77 (34%) | 47 (35%) |  |
Weight at enrollment a,c,d | 165.7 ± 40.7 | 161.8 ± 37.4 | 172.6 ± 45.3 | 0.03 |
Weight gain during pregnancy a,c,d | 28.7 ± 11.8 | 28.8 ± 11.3 | 28.6 ± 12.4 | 0.76 |