Table 1 Pregnancy and delivery characteristics of women with singleton live births ( n = 1,390,165) classified as SGA/not SGA (analyzed by chi-square and Mann–Whitney U tests)
Characteristic% or Mean (±SD) | SGA, n = 42,702 (3.1%) | Not SGA, n = 1,347,463 | p value |
|---|---|---|---|
Mean maternal age (±SD) (years) | 29.0 (±5.8) | 29.1 (±5.3) | ≤0.001 |
≤19 | 4.2 | 2.7 | ≤0.001 |
20 − 29 | 50.5 | 51.5 | |
30 − 39 | 41.2 | 42.8 | |
≥40 | 4.1 | 3.0 | |
Primiparous women | 59.6 | 40.6 | ≤0.001 |
Multiparous women | 40.4 | 59.4 | |
Mean gestational age (weeks) | 38.5 (±3.1) | 39.8 (±1.7) | ≤0.001 |
<28 | 1.9 | 0.2 | |
28 − 31 + 6 | 2.9 | 0.4 | |
32 − 36 + 6 | 12.7 | 3.5 | |
37 − 39 + 6 | 47.1 | 42.3 | |
40 − 41 + 6 | 32.5 | 48.8 | |
>42 | 2.9 | 4.8 | |
Mode of delivery | |||
Vaginal delivery | 63.0 | 78.8 | ≤0.001 |
Breech | 1.0 | 0.4 | |
Forceps | 0.1 | 0.1 | |
Vacuum assistance | 5.4 | 5.9 | |
Cesarean section | 30.5 | 14.7 | |
Girl | 48.5 | 48.9 | 0.17 |
Boy | 51.5 | 51.1 | |
Mean birthweight (±SD) (grams) | 2372.3 (±518.2) | 3590.4 (±514.4) | ≤0.001 |
Region (n = 20) range in 1987 − 2010 | 3.1 (2.9 − 3.4) | 96.9 (96.6 − 97.1) | ≤0.001 |
Time periods | |||
1987 − 1991 | 3.0 | 97.0 | ≤0.001 |
1992 − 1996 | 2.9 | 97.1 | |
1997 − 2001 | 3.1 | 96.9 | |
2002 − 2006 | 3.1 | 96.9 | |
2007 − 2010 | 3.3 | 96.7 |