TABLE 1.
Demographic characteristics, social deprivation and smoking status in 181 participants with twin pregnancies.
| Characteristic | Total n = 181 (%) | Normal outcome n = 72 (%) | Adverse outcome n = 109 (%) | Odds ratio (95% confidence interval) | Monochorionic n = 54 (%) | Dichorionic n = 127 (%) |
|---|---|---|---|---|---|---|
| Maternal age | Pseudo R 2 0.0008 | p = 0.08 | ||||
| Median (range) | 32 (27–36) | 27 (23.5–32.3) | 32 (27–36) | 0.99 (0.94–1.04) | 31 (18–43) | 27 (18–50) |
| <20 years | 4 (2.2) | 0 (0) | 4 (3.7) | Incalculable | 2 (3.7) | 2 (1.6) |
| 21–25 years | 25 (13.8) | 9 (12.5) | 16 (14.7) | 1.78 (0.67–4.69) | 12 (22.2) | 13 (10.2) |
| 26–30 years | 47 (26.0) | 16 (22.2) | 31 (28.4) | 1.94 (0.87–4.31) | 9 (16.7) | 38 (29.9) |
| 31–35 years | 56 (30.9) | 28 (38.9) | 28 (25.7) | Reference | 19 (35.2) | 37 (29.1) |
| 36–40 years | 37 (20.4) | 17 (23.6) | 20 (18.4) | 1.18 (0.51–2.70) | 8 (14.8) | 29 (22.8) |
| >41 years | 10 (5.5) | 1 (1.4) | 9 (8.3) | 9 (1.07–75.84) | 2 (3.7) | 8 (6.3) |
| Missing data | 2 (1.1) | 2 (3.7) | 0 (0) | |||
| Maternal body mass index | Pseudo R 2 0.002 | p = 0.04 | ||||
| BMI Mean ± standard deviation | 27.9 ± 6.4 | 31.9 ± 5.0 | 27.7 ± 6.8 | 0.98 ± 0.94–1.03 | 26.7 ± 6.3 | 28.5 ± 6.4 |
| <20 kg/m2 | 13 (7.2) | 1 (1.4) | 12 (11.0) | 8.36 (1.02–68.87) | 7 (13.0) | 6 (4.7) |
| 20.1–25 kg/m2 | 56 (30.9) | 23 (31.9) | 33 (30.3) | Reference | 19 (35.2) | 37 (29.1) |
| 25.1–30 kg/m2 | 55 (30.4) | 22 (30.6) | 33 (30.3) | 1.05 (0.49–2.23) | 14 (25.9) | 41 (32.3) |
| 30.1–35 kg/m2 | 29 (16.0) | 16 (22.2) | 13 (11.9) | 0.57 (0.23–1.40) | 8 (14.8) | 21 (16.5) |
| >35.1 kg/m2 | 26 (14.4) | 9 (12.5) | 17 (15.6) | 1.32 (0.50–3.46) | 6 (11.1) | 20 (15.7) |
| Missing data | 2 (1.1) | 0 (0) | 2 (1.6) | |||
| Maternal ethnicity | Pseudo R 2 0.02 | p = 0.19 | ||||
| White | 136 (75.1) | 56 (77.8) | 80 (73.4) | Reference | 44 (81.5) | 92 (72.4) |
| Black/Black British | 22 (12.2) | 10 (13.9) | 12 (11.0) | 0.84 (0.34–2.08) | 3 (5.6) | 19 (15.0) |
| Asian/Asian British | 11 (6.1) | 3 (4.2) | 8 (7.3) | 1.87 (0.47–7.35) | 4 (7.4) | 7 (5.5) |
| Any other Multiple ethnic background | 9 (5.0) | 1 (1.4) | 8 (7.3) | 5.6 (0.68–46.04) | 3 (5.6) | 6 (4.7) |
| Missing data | 3 (1.7) | 0 (0) | 3 (2.4) | |||
| Parity | Pseudo R 2 0.03 | p = 0.17 | ||||
| 0 | 85 (47.0) | 47 (65.3) | 38 (34.9) | Reference | 25 (46.3) | 60 (47.2) |
| 1 | 56 (30.9) | 22 (30.6) | 34 (31.2) | 0.80 (0.40–1.61) | 17 (31.5) | 39 (30.7) |
| 2 | 24 (13.3) | 15 (20.8) | 9 (8.3) | 0.31 (0.12–0.80) | 8 (14.8) | 16 (12.6) |
| 3 | 9 (5.0) | 3 (4.2) | 6 (5.5) | 1.04 (0.24–4.44) | 2 (3.7) | 7 (5.5) |
| >4 | 7 (3.9) | 3 (4.2) | 4 (3.7) | 0.69 (0.14–3.29) | 2 (3.7) | 5 (3.9) |
| Parous | 96 (53.0) | 43 (59.7) | 53 (48.6) | 0.64 (0.35–1.17) | 29 (53.7) | 67 (52.8) |
| Marital status | Pseudo R 2 0.001 | p = 0.89 | ||||
| Single | 30 (16.6) | 13 (18.1) | 17 (15.6) | 0.81 (0.35–1.89) | 10 (18.5) | 20 (15.7) |
| Married | 86 (47.5) | 33 (45.8) | 53 (48.6) | Reference | 22 (40.7) | 64 (50.4) |
| Cohabiting | 64 (35.4) | 26 (36.1) | 38 (34.86) | 0.91 (0.47–1.76) | 21 (38.9) | 43 (33.9) |
| Missing data | 1 (0.6) | 1 (1.9) | 0 (0) | |||
| Quintiles of Deprivation Index | Pseudo R 2 0.03 | p = 0.15 | ||||
| 1 (most deprived) | 42 (23.2) | 12 (16.7) | 30 (27.5) | 2.24 (0.88–5.70) | 14 (25.9) | 28 (22.0) |
| 2 | 31 (17.1) | 9 (12.5) | 22 (20.2) | 2.19 (0.79–6.03) | 7 (13.0) | 24 (18.9) |
| 3 | 20 (11.0) | 8 (11.1) | 12 (11.0) | 2.34 (0.44–4.07) | 6 (11.1) | 14 (11.0) |
| 4 | 37 (20.4) | 19 (26.4) | 18 (16.5) | 0.85 (0.34–2.12) | 9 (16.7) | 28 (22.0) |
| 5 (least deprived) | 36 (19.9) | 17 (23.6) | 19 (7.4) | Reference | 14 (25.9) | 22 (17.3) |
| Missing data | 15 (8.3) | 4 (7.4) | 11 (8.7) | |||
| Smoking status (early pregnancy) | Pseudo R 2 0.02 | p = 0.23 | ||||
| Current smoker | 11 (6.1) | 4 (5.6) | 7 (6.4) | 1.28 (0.35–4.61) | 4 (7.4) | 7 (5.5) |
| Stopped in pregnancy | 17 (9.4) | 3 (4.2) | 14 (12.8) | 3.41 (0.93–12.53) | 6 (11.1) | 11 (8.7) |
| Stopped prior to pregnancy | 36 (19.9) | 15 (20.8) | 21 (19.3) | 1.02 (0.48–2.19) | 11 (20.4) | 25 (19.7) |
| Never smoked | 116 (64.1) | 49 (68.1) | 67 (61.5) | Reference | 33 (61.1) | 83 (65.4) |
| Missing data | 1 (0.6) | 0 (0) | 1 (0.8) | |||
| Have you changed your smoking habits in pregnancy? (early pregnancy) | Pseudo R 2 0.02 | p = 0.27 | ||||
| Yes | 23 (12.7) | 6 (8.3) | 17 (15.6) | 1.89 (0.60–5.97) | 6 (11.1) | 17 (13.4) |
| No | 35 (19.3) | 14 (19.4) | 21 (19.3) | Reference | 12 (22.2) | 23 (18.1) |
| Missing data | 7 (3.9) | 36 (66.7) | 87 (68.5) | |||
| Was this pregnancy achieved by the use of assisted reproductive technology? | Pseudo R 2 0.0067 | p = 0.20 | ||||
| Yes | 36 (19.9) | 11 (15.3) | 25 (22.9) | 1.65 (0.76–3.61) | 6 (11.1) | 30 (23.6) |
| No | 145 (80.1) | 61 (84.7) | 84 (77.1) | Reference | 48 (88.9) | 97 (76.4) |
Note: Data are presented as total values and percentages, also presented according to chorionicity. Proportions are expressed for those with complete data and known outcomes. All data presented is taken from the first questionnaire in early pregnancy (20 weeks) (n = 181).
Bold text indicates statistically significant results.