Table 1. Characteristics of Women Included in Cohort and Their Infants.
| Characteristic | Cohort, No. (%)a | |
|---|---|---|
| Major Congenital Anomaly (n = 42 943) | Comparison (n = 428 401) | |
| Mother | ||
| Age at delivery, median (IQR), y | 28.8 (25.3-32.5) | 28.8 (25.3-32.5) |
| Parity | ||
| 1 | 20 940 (48.8) | 208 950 (48.8) |
| 2 | 14 441 (33.6) | 144 095 (33.6) |
| ≥3 | 7562 (17.6) | 75 356 (17.6) |
| Year of delivery | ||
| 1979-1993 | 20 246 (47.1) | 202 209 (47.2) |
| 1994-2003 | 11 197 (26.1) | 111 695 (26.1) |
| 2004-2013 | 11 500 (26.8) | 114 497 (26.7) |
| Married/registered partnershipb | 25 072 (58.4) | 253 752 (59.2) |
| Immigrated | 2943 (6.9) | 28 853 (6.7) |
| Lowest income quartilec | 10 723 (25.0) | 103 182 (24.1) |
| Postsecondary educationd | 10 427 (24.3) | 111 905 (26.1) |
| Pregnancy history | ||
| Spontaneous abortions | 6498 (15.1) | 58 578 (13.7) |
| Stillbirths | 405 (0.9) | 2802 (0.7) |
| Index pregnancy complications | ||
| Placentale | 2267 (5.3) | 18 356 (4.3) |
| Nonplacentalf | 114 (0.3) | 859 (0.2) |
| Medical history | ||
| Diabetes | 1463 (3.4) | 9591 (2.2) |
| Chronic hypertension | 204 (0.5) | 1329 (0.3) |
| Alcohol-related diseases | 521 (1.2) | 3732 (0.9) |
| Hypercholesterolemia | 30 (0.1) | 170 (<0.1) |
| Modified Charlson Comorbidity Index scoreg | ||
| 1 | 719 (1.7) | 6189 (1.4) |
| ≥2 | 259 (0.6) | 2074 (0.5) |
| Maternal smokingh | 5863/26 829 (21.9) | 54 177/267 447 (20.3) |
| Maternal BMIi | ||
| <25 | 6876 (59.8) | 72 507 (63.3) |
| 25-29 | 2056 (17.9) | 19 737 (17.2) |
| ≥30 | 1953 (17.0) | 16 146 (14.1) |
| Duration of follow-up, median (IQR), yj | 19.4 (9.9-27.6) | 19.5 (9.9-27.6) |
| Infant | ||
| Sex | ||
| Male | 25 475 (59.3) | 218 384 (51.0) |
| Female | 16 404 (38.2) | 209 382 (48.9) |
| Unknown | 1064 (2.5) | 635 (0.1) |
| Birth weight, g | ||
| ≤2500 | 5916 (13.8) | 17 968 (4.2) |
| >2500-4000 | 31 368 (73.0) | 344 408 (80.4) |
| >4000 | 5551 (12.9) | 64 899 (15.1) |
| Unknown | 108 (0.3) | 1126 (0.3) |
| Gestational age | ||
| <37 wk | 5455 (12.7) | 18 811 (4.4) |
| Unknown | 1245 (2.9) | 11 814 (2.8) |
| Apgar score <7 at 5 min | 1793 (4.2) | 6497 (1.5) |
| Died before end of observation period | 936 (2.2) | 1699 (0.4) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); IQR, interquartile range.
All data reflect measures at time of child’s birth unless otherwise indicated.
Missing data on 6192 (14.4%) in the exposed group and 59 911 (14.0%) in the comparison cohort.
Data available starting in 1980; for mothers who gave birth in 1979, data from 1980 were used for the baseline. Missing data on 265 (0.6%) in the exposed group and 2519 (0.6%) in the comparison cohort.
Data available starting in 1981; for mothers who gave birth in 1979-1980, data from 1981 were used for the baseline. Missing data on 2158 (5.0%) in the exposed group and 20 352 (4.8%) in the comparison cohort.
Includes preeclampsia, gestational or unspecified hypertension, placental abruption, or placental infarction.
Includes intrauterine hypoxia and birth asphyxia, uterine rupture, umbilical cord prolapse, vasa previa, amniotic fluid embolism, fetal-maternal hemorrhage, or chorioamnionitis.
Includes comorbid conditions with various weights. The modified index excludes diabetes and liver diseases associated with alcohol use.
Data only available starting in 1991 (26 829 women in the exposed group and 267 447 women in the comparison cohort). Missing data on 1484 (5.5%) in the exposed group and 11 421 (4.3%) in the comparison cohort.
Data only available starting in 2004 (11 500 women in the exposed group and 114 497 women in the comparison cohort). Missing data on 615 (5.3%) in the exposed group and 6107 (5.3%) in the comparison cohort.
Follow-up time only measured at 1 year after the birth of the child.