Table 1.
Baseline characteristics and perinatal outcomes.
| PTB in the subsequent pregnancy | Full-term birth in the subsequent pregnancy | p-valuea | p-valueb | ||
|---|---|---|---|---|---|
| sPTB | mPTB | ||||
| n = 52 | n = 36 | n = 1591 | |||
| Index pregnancy | |||||
| Tertiary center | 37 (71.2) | 34 (94.4) | 721 (45.3) | < 0.001* | < 0.001* |
| Maternal age, years | 30.4 ± 5.6 | 30.5 ± 5.1 | 30.5 ± 4.8 | 0.890 | 0.981 |
| Maternal age ≥ 35 years | 13 (25.0) | 8 (22.2) | 292 (18.4) | 0.225 | 0.554 |
| Maternal age < 20 years | 2 (3.8) | 0 (0) | 27 (1.7) | 0.233 | 1.000 |
| Pre-pregnancy BMI, kg/m2 | 20.4 ± 3.3 | 22.1 ± 5.1 | 20.9 ± 3.4 | 0.308 | 0.192 |
| Pre-pregnancy BMI ≥ 25.0 kg/m2 | 4 (7.7) | 8 (22.2) | 140 (8.8) | 0.781 | 0.013* |
| Pre-pregnancy BMI < 18.5 kg/m2 | 16 (30.8) | 7 (19.4) | 305 (19.2) | 0.038* | 0.967 |
| Smokers | 1 (1.9) | 0 (0.0) | 16 (1.0) | 0.284 | 1.000 |
| Chronic hypertension | 2 (3.8) | 3 (8.3) | 16 (1.0) | 0.117 | 0.009* |
| Pre-exisiting DM | 0 (0.0) | 4 (11.1) | 13 (0.8) | 1.000 | < 0.001* |
| Hyperthyroidism | 0 (0.0) | 1 (2.8) | 12 (0.8) | 1.000 | 0.323 |
| Hypothyroidism | 1 (1.9) | 2 (5.6) | 30 (1.9) | 1.000 | 0.241 |
| Nulliparity | 38 (73.1) | 26 (72.2) | 1275 (80.1) | 0.211 | 0.241 |
| ART | 5 (9.6) | 4 (11.1) | 133 (8.4) | 0.593 | 0.519 |
| Gestational body weight gain, kg | 9.9 ± 4.0 | 9.4 ± 5.2 | 11.0 ± 3.9 | 0.051 | 0.019* |
| HDP | 8 (15.4) | 11 (30.6) | 186 (11.7) | 0.425 | 0.002* |
| PE | 1 (1.9) | 7 (19.4) | 46 (2.9) | 1.000 | < 0.001* |
| GDM | 5 (9.6) | 3 (8.3) | 67 (4.2) | 0.083 | 0.211 |
| GA at delivery, weeks | 37.5 ± 2.4 | 36.9 ± 3.3 | 39.3 ± 1.9 | < 0.001* | < 0.001* |
| Preterm birth (< 37 weeks) | 17 (32.7) | 12 (33.3) | 89 (5.6) | < 0.001* | < 0.001* |
| Spontaneous | 16 (30.8) | 3 (8.3) | 50 (3.1) | < 0.001* | 0.110 |
| Medically indicated | 1 (1.9) | 9 (25.0) | 39 (2.5) | 1.000 | < 0.001* |
| Cesarean section | 3 (5.8) | 25 (69.4) | 382 (24.0) | 0.002* | < 0.001* |
| Neonatal sex, male | 34 (65.4) | 21 (58.3) | 852 (53.6) | 0.092 | 0.569 |
| Neonatal height, cm | 48.7 ± 2.7 | 46.4 ± 5.7 | 49.6 ± 2.6 | 0.015* | 0.002* |
| Birthweight, g | 2,706 ± 517 | 2,526 ± 743 | 3,002 ± 467 | < 0.001* | < 0.001* |
| Large for gestational age infant | 3 (5.8) | 4 (11.1) | 181 (11.4) | 0.207 | 1.000 |
| Small for gestational age infant | 0 (0) | 2 (5.6) | 30 (1.9) | 1.000 | 0.156 |
| Placental weight, g | 539.1 ± 106.7 | 493.4 ± 149.9 | 575.2 ± 111.0 | 0.021* | 0.002* |
| Interpregnancy | |||||
| Pregnancy interval, years | 2.3 ± 1.0 | 2.7 ± 1.7 | 2.2 ± 0.9 | 0.427 | 0.111 |
| ΔBMI, kg/m2 | 0.04 ± 1.91 | 0.64 ± 2.09 | 0.44 ± 1.39 | 0.044* | 0.580 |
| Anuual BMI change, kg/m2/year | − 0.08 ± 1.41 | 0.31 ± 1.34 | 0.22 ± 0.78 | 0.007* | 0.690 |
| Subsequent pregnancy | |||||
| Maternal age, years | 32.8 ± 5.7 | 33.2 ± 5.0 | 32.8 ± 5.0 | 0.994 | 0.570 |
| Pre-pregnancy BMI, kg/m2 | 20.5 ± 3.3 | 22.7 ± 5.4 | 21.4 ± 3.6 | 0.079 | 0.144 |
| Pre-pregnancy BMI ≥ 25.0 kg/m2 | 4 (7.7) | 8 (22.2) | 183 (11.5) | 0.395 | 0.062 |
| Pre-pregnancy BMI < 18.5 kg/m2 | 14 (26.9) | 7 (19.4) | 270 (17.0) | 0.062 | 0.696 |
| ART | 5 (9.6) | 3 (8.3) | 132 (8.3) | 0.616 | 0.755 |
| Gestational body weight gain, kg | 8.4 ± 3.6 | 7.4 ± 4.8 | 10.3 ± 3.6 | < 0.001* | 0.019* |
| HDP | 1 (1.9) | 14 (38.9) | 122 (7.7) | 0.176 | < 0.001* |
| PE | 0 (0.0) | 12 (33.3) | 19 (1.2) | 1.000 | < 0.001* |
| GDM | 4 (7.7) | 7 (19.4) | 142 (8.9) | 1.000 | 0.031* |
| GA at delivery, weeks | 35.4 ± 1.7 | 33.9 ± 3 | 39.2 ± 1.1 | < 0.001* | < 0.001* |
| 22 to < 32 weeks | 4 (7.7) | 5 (13.9) | 0 (0.0) | < 0.001* | < 0.001* |
| 32 to < 37 weeks | 48 (92.3) | 31 (86.1) | 0 (0.0) | < 0.001* | < 0.001* |
| Cesarean section | 0 (0.0) | 32 (88.9) | 374 (23.5) | < 0.001* | < 0.001* |
| Neonatal sex, male | 29 (55.8) | 16 (44.4) | 807 (51.5) | 0.541 | 0.405 |
| Neonatal height, cm | 46.6 ± 2.8 | 43.5 ± 6.1 | 50.0 ± 1.7 | < 0.001* | < 0.001* |
| Birthweight, g | 2432 ± 424 | 1977 ± 780 | 3095 ± 367 | < 0.001* | < 0.001* |
| Large for gestational age infant | 7 (13.5) | 1 (2.8) | 183 (11.5) | 0.756 | 0.345 |
| Small for gestational age infant | 0 (0.0) | 4 (18.2) | 12 (0.9) | 1.000 | < 0.001* |
| Placental weight, g | 543.2 ± 109.9 | 450.7 ± 200.4 | 587.6 ± 108.1 | 0.004* | < 0.001* |
PTB, preterm birth; sPTB, spontaneous PTB; mPTB, medically indicated PTB; GDM, gestational diabetes mellitus; BMI, body mass index; DM, diabetes mellitus; ART, assisted reproductive technology; GA, gestational age; HDP, hypertensive disorders of pregnancy; PE, preeclampsia.
Data are presented as means ± standard deviation for continuous variables and n (%) for discrete variables.
*Statistically significant.
Significant values are in bold.
ap-value for compareing full-term birth group and sPTB; bp-value for compareing full-term birth group and mPTB.