Table 1.
Selected maternal characteristics by NVP symptoms, adjusted risk ratios (RR) and 95% confidence interval (CI) on maternal characteristics in relation with symptom severity: right from the start (2000–2004), n = 2,407
| Symptom severitya | |||||
|---|---|---|---|---|---|
| No symptoms (n = 279) |
Having nausea only (n = 852) |
Having both symptoms of nausea and vomiting (n = 1,274) |
|||
| n (%) | n (%) | Adj. RRa,b (95% CI) | n (%) | Adj. RRb,c (95% CI) | |
| Maternal age | |||||
| <25 years old | 76 (27.2) | 159 (18.7) | 1.0 (0.8, 1.3) | 490 (38.5) | 1.1 (1.0, 1.2) |
| 25–29 years old | 84 (30.1) | 281 (33.1) | 1.0 Reference | 380 (29.7) | 1.0 Reference |
| 30–34 years old | 70 (25.1) | 279 (32.5) | 1.0 (0.8, 1.2) | 305 (23.9) | 1.0 (0.9, 1.1) |
| ≥35 years old | 49 (17.6) | 134 (15.7) | 0.9 (0.8, 1.2) | 99 (7.8) | 0.8 (0.7, 0.9) |
| Race/ethnicity | |||||
| Non-Hispanic White | 137 (49.1) | 555 (65.2) | 1.0 Reference | 662 (51.2) | 1.0 Reference |
| Non-Hispanic Black | 112 (40.1) | 213 (25.0) | 0.9 (0.8, 1.0) | 437 (34.4) | 0.9 (0.9, 1.0) |
| Hispanic | 22 (7.9) | 56 (6.6) | 0.9 (0.8, 1.1) | 130 (10.1) | 1.0 (0.9, 1.1) |
| Asian/other | 8 (2.9) | 27 (3.1) | 1.0 (0.8, 1.2) | 54 (4.3) | 1.1 (1.0, 1.2) |
| Education | |||||
| <12 years | 94 (33.7) | 172 (20.2) | 0.9 (0.8, 1.0) | 446 (35.0) | 1.0 (0.9, 1.1) |
| ≥12 to <16 years | 47 (16.9) | 159 (18.7) | 1.0 (0.9, 1.1) | 310 (24.4) | 1.1 (1.0, 1.2) |
| ≥16 years | 138 (49.5) | 521 (61.2) | 1.0 Reference | 517 (40.6) | 1.0 Reference |
| Marital status | |||||
| Married | 169 (60.6) | 658 (77.3) | 1.0 Reference | 758 (59.5) | 1.0 Reference |
| Other | 110 (39.4) | 193 (22.7) | 0.9 (0.8, 1.0) | 516 (40.36) | 1.0 (0.9, 1.0) |
| Smokingb | |||||
| Any | 16 (5.8) | 30 (3.5) | – | 85 (6.7) | – |
| None | 263 (94.3) | 822 (96.5) | – | 1,189 (93.3) | – |
| Alcohol use | |||||
| Any | 11 (4.0) | 22 (2.6) | 0.8 (0.7, 1.1) | 25 (2.0) | 0.9 (0.7, 1.1) |
| None | 266 (96.0) | 830 (97.4) | 1.0 Reference | 1,249 (98.0) | 1.0 Reference |
| Age at menarche | |||||
| ≤11 years old | 59 (21.5) | 177 (21.0) | 1.1 (1.0, 1.2) | 295 (23.3) | 1.0 (1.0, 1.1) |
| 12–13 years old | 132 (48.0) | 460 (54.5) | 1.1 (1.0, 1.2) | 664 (52.4) | 1.1 (1.0, 1.1) |
| ≥14 years old | 84 (30.7) | 207 (24.5) | 1.0 Reference | 308 (24.3) | 1.0 Reference |
| Pregnancy loss (SAB) history | |||||
| No prior SAB | 88 (31.5) | 244 (28.6) | 1.0 Reference | 387 (30.4) | 1.0 Reference |
| ≥1 pregnancy with no SAB | 150 (53.8) | 426 (50.0) | 1.0 (0.9, 1.1) | 601 (47.2) | 1.0 (1.0, 1.1) |
| ≥1 pregnancy with ≥1 SAB | 41 (14.7) | 182 (21.4) | 1.1 (1.0, 1.2) | 286 (22.5) | 1.1 (1.0, 1.2) |
| Gravidityb | |||||
| Primigravid | 93 (33.3) | 251 (29.5) | – | 403 (31.6) | – |
| 2 | 89 (31.9) | 282 (33.0) | – | 373 (29.3) | – |
| 3 | 45 (16.1) | 170 (20.0) | – | 254 (19.9) | – |
| ≥4 | 52 (18.6) | 149 (17.5) | – | 244 (19.2) | – |
| Infant genderd | |||||
| Female baby | 77 (42.1) | 318 (46.5) | 1.0 (1.0, 1.1) | 582 (51.2) | 1.1 (1.0, 1.1) |
| Male baby | 106 (57.9) | 366 (53.5) | 1.0 Reference | 554 (48.8) | 1.0 Reference |
NVP Nausea and vomiting during early pregnancy
a
Cannot determine severity for n = 2 women
b
Model adjusted for maternal age, race/ethnicity, education, marital status, alcohol use, age at menarche, and pregnancy loss history; smoking and gravidity were not retained in the final model based on pre-determined selection criteria outlined in “Methods” section
c
Compared to women with no nausea and vomiting symptoms
d
Analysis of infant gender was restricted to women with singleton live births (n = 2,149)