Table 1.
Characteristics of mothers of neural tube defect cases and controls, Birth Defects Study, 1998–2015
| Characteristic | NTD cases (n = 375) | Controls (n = 8247) | Controls only
|
|
|---|---|---|---|---|
| Reported periconceptional fever (n = 154) | No reported fever during pregnancy (n = 8093) | |||
|
N (%) |
N (%) |
N (%) |
N (%) |
|
| Maternal age (years) | ||||
| <20 | 33 (8.8) | 591 (7.2) | 7 (4.5) | 584 (7.2) |
| 20–24 | 66 (17.6) | 1232 (14.9) | 21 (13.6) | 1211 (15.0) |
| 25–29 | 113 (30.1) | 2203 (26.7) | 47 (30.5) | 2156 (26.6) |
| 30–34 | 103 (27.5) | 2710 (32.9) | 48 (31.2) | 2662 (32.9) |
| 35–39 | 54 (14.4) | 1270 (15.4) | 24 (15.6) | 1246 (15.4) |
| 40+ | 6 (1.6) | 220 (2.7) | 6 (3.9) | 214 (2.6) |
| Unknown | 0 (0.0) | 21 (0.3) | 1 (0.6) | 20 (0.2) |
| Maternal education | ||||
| < High school | 59 (15.7) | 793 (9.6) | 7 (4.5) | 786 (9.7) |
| High school | 89 (23.7) | 1614 (19.6) | 19 (12.3) | 1595 (19.7) |
| > High school | 226 (60.3) | 5830 (70.7) | 128 (83.1) | 5702 (70.5) |
| Missing | 1 (0.3) | 10 (0.1) | 0 (0.0) | 10 (0.1) |
| Maternal race/ethnicity | ||||
| Non-Hispanic white | 211 (56.3) | 5326 (64.6) | 115 (74.7) | 5211 (64.4) |
| Non-Hispanic black | 51 (13.6) | 726 (8.8) | 8 (5.2) | 718 (8.9) |
| Hispanic | 78 (20.8) | 1428 (17.3) | 12 (7.8) | 1416 (17.5) |
| Other | 35 (9.3) | 751 (9.1) | 18 (11.7) | 733 (9.1) |
| Missing | 0 (0.0) | 16 (0.2) | 1 (0.6) | 15 (0.2) |
| Study center | ||||
| Massachusetts | 59 (15.7) | 3990 (48.4) | 69 (44.8) | 3921 (48.4) |
| Philadelphia | 108 (28.8) | 1516 (18.4) | 32 (20.8) | 1484 (18.3) |
| Toronto | 83 (22.1) | 483 (5.9) | 17 (11.0) | 466 (5.8) |
| San Diego | 66 (17.6) | 1338 (16.2) | 21 (13.6) | 1317 (16.3) |
| New York | 50 (13.3) | 828 (10.0) | 14 (9.1) | 814 (10.1) |
| Nashville | 9 (2.4) | 92 (1.1) | 1 (0.6) | 91 (1.1) |
| Body mass index (kg/m2) | ||||
| Underweight (<18.5) | 17 (4.5) | 345 (4.2) | 4 (2.6) | 341 (4.2) |
| Normal weight (18.5–24.9) | 178 (47.5) | 4914 (59.6) | 93 (60.4) | 4821 (59.6) |
| Overweight (25.0–29.9) | 93 (24.8) | 1676 (20.3) | 38 (24.7) | 1638 (20.2) |
| Obese (30+) | 68 (18.1) | 1076 (13.0) | 18 (11.7) | 1058 (13.1) |
| Missing | 19 (5.1) | 236 (2.9) | 1 (0.6) | 235 (2.9) |
| Year of last menstrual period | ||||
| 1997–2002 | 133 (35.5) | 3296 (40.0) | 77 (50.0) | 3219 (39.8) |
| 2003–2008 | 112 (29.9) | 1878 (22.8) | 40 (26.0) | 1838 (22.7) |
| 2009–2014 | 130 (34.7) | 3073 (37.3) | 37 (24.0) | 3036 (37.5) |
| Periconceptional* folic acid† | ||||
| ≥400 mcg | 165 (44.0) | 4247 (51.5) | 89 (57.8) | 4158 (51.4) |
| <400 mcg | 195 (52.0) | 3794 (46.0) | 63 (40.9) | 3731 (46.1) |
| Missing | 15 (4.0) | 206 (2.5) | 2 (1.3) | 204 (2.5) |
| Periconceptional* antipyretic use | ||||
| Yes | 124 (33.1) | 2703 (32.8) | 93 (60.4) | 2610 (32.3) |
| No | 176 (46.9) | 3889 (47.2) | 34 (22.1) | 3855 (47.6) |
| Uncertain | 75 (20.0) | 1655 (20.1) | 27 (17.5) | 1628 (20.1) |
| Periconceptional* illness, without reported fever | ||||
| Yes | 30 (8.0) | 475 (5.8) | 12 (7.8) | 463 (5.7) |
| No | 345 (92.0) | 7772 (94.2) | 142 (92.2) | 7630 (94.3) |
*
Defined as the 28 days before to the 28 days after the last menstrual period.
†
Average daily folic acid intake from supplements and diet in the periconceptional period.