Background
Methods
Study design
Data collection
Exposure variables
Obstetric outcomes and confounding factors
Statistical analyses
Results
MSD < 6.0 h | MSD 6.0–7.9 h | MSD 8.0–8.9 h | MSD 9.0–9.9 h | MSD 10.0–12.0 h | p-value | |
---|---|---|---|---|---|---|
Variable | n = 3958 | n = 37,944 | n = 23,769 | n = 11,976 | n = 4524 | |
Maternal medical background | ||||||
Maternal age (years), mean ± SD | 31.7 ± 5.5 | 31.7 ± 4.9 | 31.5 ± 4.7 | 30.9 ± 4.8 | 29.1 ± 5.2 | < 0.001 |
BMI (kg/m2) before pregnancy, mean ± SD | 21.4 ± 3.6 | 21.2 ± 3.3 | 21.3 ± 3.2 | 21.3 ± 3.4 | 21.3 ± 3.4 | < 0.001 |
Nulliparous, % (n) | 51.6 (2043) | 47.7 (18,096) | 32.7 (7761) | 25.0 (2992) | 37.1 (1679) | < 0.001 |
Smoking during pregnancy, % (n) | 8.9 (352) | 4.6 (1751) | 4.1 (971) | 4.0 (475) | 6.3 (284) | < 0.001 |
Alcohol consumption, % (n) | 3.8 (149) | 2.7 (1008) | 3.0 (707) | 3.2 (384) | 2.5 (114) | < 0.001 |
Maternal educational status, % (n) | ||||||
< 10 years | 7.3 (289) | 3.8 (1442) | 3.9 (929) | 4.9 (588) | 9.0 (406) | < 0.001 |
10–12 years | 35.1 (1390) | 29.8 (11,296) | 30.0 (7135) | 31.5 (3778) | 37.6 (1699) | < 0.001 |
13–16 years | 56.3 (2227) | 64.8 (24,599) | 64.6 (15,359) | 62.2 (7445) | 52.7 (2383) | < 0.001 |
≥ 17 years | 1.3 (52) | 1.6 (607) | 1.5 (346) | 1.4 (165) | 0.8 (36) | < 0.001 |
Annual household income, % (n) | ||||||
< 2,000,000 JPY | 7.6 (302) | 4.5 (1708) | 5.1 (1209) | 7.2 (862) | 11.8 (533) | < 0.001 |
2,000,000–5,999,999 JPY | 66.3 (2624) | 65.8 (24,986) | 68.1 (16,178) | 70.4 (8426) | 73.7 (3333) | < 0.001 |
6,000,000–9,999,999 JPY | 21.6 (856) | 25.1 (9524) | 22.5 (5354) | 18.7 (2244) | 12.0 (544) | < 0.001 |
≥ 10,000,000 JPY | 4.4 (176) | 4.5 (1726) | 4.3 (1028) | 3.7 (444) | 2.5 (114) | < 0.001 |
GWG (kg), mean ± SD | 10.3 ± 4.3 | 10.2 ± 4.8 | 10.3 ± 5.9 | 10.2 ± 4.1 | 10.6 ± 4.3 | < 0.001 |
Excessive GWG, ≥ 12 kg, % (n) | 33.6 (1331) | 30.8 (11,690) | 31.2 (7423) | 31.9 (3819) | 36.9 (1669) | < 0.001 |
Obstetric outcomes | ||||||
PTB, < 37 weeks, % (n) | 4.7 (185) | 4.4 (1660) | 4.5 (1058) | 4.3 (516) | 4.5 (205) | 0.86 |
Neonatal birth weight (g), mean ± SD | 3017 ± 419 | 3022 ± 412 | 3037 ± 410 | 3044 ± 406 | 3030 ± 410 | < 0.001 |
LBW infants < 2500 g, % (n) | 8.3 (330) | 8.2 (3101) | 7.6 (1803) | 7.0 (837) | 7.2 (327) | < 0.001 |
VLBW infants < 1500 g, % (n) | 0.5 (20) | 0.5 (177) | 0.4 (101) | 0.4 (51) | 0.6 (25) | 0.87 |
SGA infants, % (n) | 4.7 (187) | 5.1 (1951) | 4.9 (1173) | 4.7 (558) | 5.0 (224) | 0.25 |
Macrosomia, > 4000 g, % (n) | 1.0 (41) | 0.8 (318) | 0.9 (211) | 1.0 (119) | 0.8 (35) | 0.38 |
Obstetric outcomes | LBW infants | VLBW infants | SGA infants | Macrosomia |
---|---|---|---|---|
< 2500 g | < 1500 g | |||
cORs and aORs (95% CI) | ||||
MSD < 6.0 h | ||||
cORs | 1.02 (0.91–1.15) | 1.08 (0.68–1.72) | 0.92 (0.78–1.07) | 1.24 (0.89–1.72) |
Model 1 | 0.95 (0.83–1.08) | 1.01 (0.62–1.65) | 0.88 (0.75–1.02) | 1.23 (0.89–1.71) |
Model 2 | 0.95 (0.83–1.09) | 1.02 (0.62–1.67) | 0.89 (0.76–1.03) | 1.19 (0.86–1.66) |
MSD 6.0–7.9 h | ||||
Ref | Ref | Ref | Ref | |
MSD 8.0–8.9 h | ||||
cORs | 0.92 (0.87–0.98) | 0.91 (0.71–1.16) | 0.96 (0.89–1.03) | 1.06 (0.89–1.26) |
Model 1 | 0.96 (0.90–1.03) | 0.95 (0.73–1.23) | 0.96 (0.90–1.04) | 1.01 (0.84–1.20) |
Model 2 | 0.97 (0.91–1.04) | 0.95 (0.73–1.24) | 0.97 (0.90–1.04) | 0.99 (0.83–1.19) |
MSD 9.0–9.9 h | ||||
cORs | 0.84 (0.78–0.91) | 0.91 (0.67–1.25) | 0.90 (0.82–0.99) | 1.19 (0.96–1.47) |
Model 1 | 0.90 (0.83–0.99) | 0.99 (0.71–1.37) | 0.91 (0.82–0.99) | 1.10 (0.89–1.36) |
Model 2 | 0.92 (0.84–1.00) | 0.99 (0.71–1.38) | 0.91 (0.83–1.00) | 1.08 (0.87–1.34) |
MSD 10.0–12.0 h | ||||
cORs | 0.88 (0.88–0.99) | 1.19 (0.78–1.80) | 0.96 (0.83–1.11) | 0.92 (0.65–1.31) |
Model 1 | 0.86 (0.76–0.99) | 1.27 (0.81–1.99) | 0.95 (0.83–1.10) | 0.89 (0.63–1.27) |
Model 2 | 0.90 (0.78–1.03) | 1.31 (0.83–2.06) | 0.98 (0.85–1.13) | 0.86 (0.60–1.23) |
Obstetric outcome | Appropriate GWG | Excessive GWG | ||
---|---|---|---|---|
LBW infants | SGA infants | LBW infants | SGA infants | |
cORs and aORs (95% CI) | ||||
MSD < 6.0 h | ||||
cORs | 1.07 (0.94–1.22) | 0.97 (0.82–1.15) | 0.92 (0.68–1.24) | 0.79 (0.55–1.14) |
aORs | 0.98 (0.84–1.13) | 0.92 (0.78–1.09) | 0.85 (0.61–1.17) | 0.75 (0.52–1.08) |
MSD 6.0–7.9 h | ||||
Ref | Ref | Ref | Ref | |
MSD 8.0–8.9 h | ||||
cORs | 0.94 (0.88–1.00) | 0.95 (0.88–1.03) | 0.86 (0.73–1.00) | 1.00 (0.84–1.18) |
aORs | 0.99 (0.92–1.06) | 0.96 (0.88–1.04) | 0.90 (0.76–1.06) | 1.00 (0.84–1.19) |
MSD 9.0–9.9 h | ||||
cORs | 0.83 (0.76–0.90) | 0.87 (0.78–0.97) | 0.97 (0.80–1.17) | 1.08 (0.88–1.33) |
aORs | 0.88 (0.80–0.97) | 0.87 (0.78–0.97) | 1.10 (0.89–1.35) | 1.07 (0.87–1.32) |
MSD 10.0–12.0 h | ||||
cORs | 0.90 (0.79–1.03) | 0.96 (0.81–1.13) | 1.01 (0.78–1.31) | 1.14 (0.85–1.51) |
aORs | 0.89 (0.76–1.04) | 0.87 (0.76–1.01) | 0.92 (0.69–1.23) | 1.08 (0.81–1.44) |