Table 4.
Risks of Adverse Pregnancy Outcomes by Maternal Fertility Group and Infant Gender
| Fertility | All Twins | Like Gender | Unlike Gender | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Outcome | Group | % | ARR | 95% CI | % | ARR | 95% CI | % | ARR | 95% CI |
| Pregnancy Outcomes1 | ||||||||||
| Gestational | Fertile | 8.1 | 1.00 | Reference | 8.3 | 1.00 | Reference | 7.6 | 1.00 | Reference |
| Diabetes2 | Subfertile | 11.6 | 1.42 | 1.13, 1.79 | 10.0 | 1.15 | 0.83, 1.59 | 13.5 | 1.85 | 1.32, 2.61 |
| IVF | 10.7 | 1.23 | 1.06, 1.43 | 10.4 | 1.07 | 0.92, 1.25 | 11.0 | 1.44 | 1.13, 1.83 | |
| Pregnancy | Fertile | 20.5 | 1.00 | Reference | 20.1 | 1.00 | Reference | 21.4 | 1.00 | Reference |
| Hypertension3 | Subfertile | 26.7 | 1.21 | 1.06, 1.39 | 28.4 | 1.31 | 1.10, 1.57 | 24.6 | 1.09 | 0.87, 1.35 |
| IVF | 25.5 | 1.15 | 1.06, 1.26 | 25.3 | 1.16 | 1.04, 1.30 | 25.6 | 1.12 | 0.98, 1.28 | |
| Uterine | Fertile | 1.0 | 1.00 | Reference | 1.0 | 1.00 | Reference | 1.1 | 1.00 | Reference |
| Bleeding | Subfertile | 1.9 | 1.92 | 1.06, 3.50 | 2.3 | 2.59 | 1.21, 5.55 | 1.5 | 1.27 | 0.48, 3.35 |
| IVF | 2.9 | 2.58 | 1.80, 3.69 | 2.6 | 2.71 | 1.70, 4.31 | 3.2 | 2.30 | 1.30, 4.07 | |
| Placental | Fertile | 3.0 | 1.00 | Reference | 3.1 | 1.00 | Reference | 2.7 | 1.00 | Reference |
| Complications | Subfertile | 5.9 | 2.07 | 1.46, 2.93 | 6.1 | 2.20 | 1.41, 3.44 | 5.7 | 2.00 | 1.14, 3.52 |
| IVF | 5.1 | 1.83 | 1.45, 2.31 | 5.3 | 1.91 | 1.42, 2.57 | 4.9 | 1.82 | 1.22, 2.70 | |
| Prenatal | Fertile | 15.8 | 1.00 | Reference | 16.3 | 1.00 | Reference | 14.8 | 1.00 | Reference |
| Hospitalizations | Subfertile | 17.4 | 1.28 | 1.07, 1.53 | 16.1 | 1.11 | 0.87, 1.42 | 18.9 | 1.48 | 1.13, 1.92 |
| IVF | 16.5 | 1.24 | 1.11, 1.38 | 17.1 | 1.10 | 0.98, 1.24 | 16 | 1.30 | 1.09, 1.55 | |
| Primary | Fertile | 52.8 | 1.00 | Reference | 52.6 | 1.00 | Reference | 53.1 | 1.00 | Reference |
| Cesarean4 | Subfertile | 60.2 | 1.12 | 1.05, 1.20 | 58.8 | 1.12 | 1.03, 1.22 | 61.9 | 1.13 | 1.03, 1.24 |
| IVF | 65.4 | 1.17 | 1.13, 1.21 | 64.2 | 1.16 | 1.10, 1.22 | 66.7 | 1.19 | 1.12, 1.26 | |
| Primary | Fertile | 69.0 | 1.00 | Reference | 67.9 | 1.00 | Reference | 71.5 | 1.00 | Reference |
| Cesarean (nulliparas)5 | Subfertile | 68.6 | 1.04 | 0.94, 1.16 | 64.9 | 1.11 | 0.96, 1.28 | 73.1 | 1.00 | 0.87, 1.15 |
| IVF | 78.7 | 0.87 | 0.82, 0.92 | 76.7 | 1.16 | 1.07, 1.26 | 80.8 | 1.07 | 0.99, 1.16 | |
Models adjusted for parental ages, race/ethnicity, education, payor status, and maternal smoking; maternal pre-existing conditions (diabetes mellitus and chronic hypertension), parity; fertile women are the reference group.
Models adjusted for parental ages, race/ethnicity, education, and payor status; smoking, maternal pre-existing conditions (diabetes mellitus and chronic hypertension), parity.
Models for gestational diabetes adjusted for all factors in model 1 except diabetes mellitus.
Models for pregnancy hypertension adjusted for all factors in model 1 except chronic hypertension.
Models adjusted for parental ages, race/ethnicity, education, and payor status; smoking, maternal pre-existing conditions (diabetes mellitus and chronic hypertension), parity, and breech/malpresentation, cephalopelvic disproportion.
Model adjusted for all factors in model 4 except parity. Bolded values indicate ARRs and 95% CIs which are significantly greater than the reference group. Bolded values indicate ARRs and 95% CIs which are significantly greater than the reference group.