Table 3.
Descriptive variables in spontaneous and induced preterm births.a
| Descriptive variable | SPTB | IPTB | P value (ANOVA) |
|---|---|---|---|
| Gestational age at enrollment (days) | 144.8±51, 143 (46–254) | 130.7±45.3, 130 (44–247) | <0.001 |
| Maternal age (years) | 24.6±6, 24 (16–43) | 25.3±6.2, 25 (16–43) | 0.142 |
| Maternal weight (kg) | 59.5±14, 56.6 (34–129.8) | 64±15.2, 61.2 (37.6–125.2) | <0.001 |
| Maternal length (cm) | 158±6, 158 (141–177) | 158±6, 158 (141–179) | 0.993 |
| Maternal head circumference (mm) | 542±19, 540 (485–602) | 545±19, 545 (500–600) | 0.040b |
| Maternal mid upper arm circumference (mm) | 262.5±43.4, 251.3 (185–535) | 277.1±47.6, 270 (189.5–475) | <0.001 |
| BMI (kg/m2) | 23.9±5.3, 22.5 (14.9–50.1) | 25.8±5.9, 24.9 (15.4–48.9) | <0.001 |
| Gravidity | 2.3±1.4, 2 (1–9) | 2.2±1.4, 2 (1–7) | 0.437 |
| Maternal education years | 9.6±1.7, 10 (3–13) | 10±1.7, 10 (5–13) | 0.005 |
| Household income (Rands c) | 802.4±609.8, 666.7 (71.4–3000) | 925.6±644.4, 750 (71.4–3000) | 0.049 |
| Edinburgh Depression Score d | 13.6±6.1, 14 (0–30) | 12.9±5.8, 13 (0–28) | 0.141 |
| Birth weight (g) | 2244.1±626.1, 2330 (460–4440) | 1954.6±791.9, 2075 (190–4630) | <0.001 |
| Birth weight Z-score | −0.3±1, −0.2 (−6.3 to 3.2) | −0.7±1.2, −0.6 (−5.7 to 3.7) | <0.001 |
| Birth weight centile | 42.8±26.8, 41.7 (0–99.9) | 30.8±25.8, 26.7 (0–100) | <0.001 |
| Days kept in hospital | 5.5±12.9, 1 (0–97) | 10.6±19.1, 3 (0–110) | <0.001 |
| P value (χ2) | |||
| Marital status: married | 101 (20.0) | 58 (25.9) | 0.205 |
| Poor housing e | 140 (33.5) | 56 (28.4) | 0.206 |
| Maternal underweight | 40 (8.1) | 12 (5.5) | 0.211 |
| Maternal obesity | 61 (12.3) | 49 (22.4) | <0.001 |
| Telephone | 336 (80.8) | 179 (90.9) | <0.001 |
| Water at home | 310 (74.3) | 167 (84.8) | 0.003 |
| Drinking of alcohol during pregnancy | 336 (68.7) | 136 (65.1) | 0.347 |
| Smoking of cigarettes during pregnancy | 376 (76.9) | 152 (72.7) | 0.240 |
| Use of marijuana | 59 (12.7) | 21 (10.4) | 0.392 |
| Use of methamphetamine | 43 (9.3) | 14 (7.0) | 0.314 |
| Primigravida | 186 (41.0) | 95 (44.8) | 0.350 |
| Previous stillbirth | 17 (6.3) | 7 (6.0) | 0.893 |
| Previous preterm birth | 81 (30.2) | 31 (26.5) | 0.456 |
| Placental abruption f | 15 (3.0) | 21 (9.4) | <0.001 |
| Pre-eclampsia f | 13 (2.6) | 53 (23.9) | <0.001 |
| Eclampsiaf | 3 (0.6) | 4 (1.8) | 0.149 |
| Diabetes f | 7 (1.4) | 5 (2.4) | 0.407 |
| Gestational hypertension f | 34 (6.8) | 98 (44.0) | <0.001 |
| LBW infants | 310 (61.3) | 163 (73.4) | 0.001 |
| SGA infants | 64 (12.9) | 60 (27.8) | <0.001 |
| Infant in NICU | 125 (27.3) | 87 (47.0) | <0.001 |
Abbreviations: ANOVA, analysis of variance; BMI, body mass index; IPTB, induced preterm birth; LBW, low birth weight; NICU, neonatal intensive care unit; SD, standard deviation; SGA, small for gestational age; SPTB, spontaneous preterm birth.
a
Values are given as mean ± SD, median (range), or number (percentage).
b
Mann–Whitney U test.
c
1 USD = 15.22 Rands.
d
Validated.
e
Small model toy house (Wendy), informal shack, shelter, trailer.
f
Current pregnancy.