Background
Methods
Study design and data source
Ethics statement
Selection of study population
Study variables and outcome measures
Covariates
Statistical analysis
Results
Study population
Characteristics of the study cohort
Characteristics | Total (n = 17,048) | Maternal BMI, kg/m2 | P-value | ||
---|---|---|---|---|---|
< 30 (n = 15,878) | 30–39 (n = 653) | ≥ 40 (n = 517) | |||
Demography
| |||||
Age | |||||
< 25 | 179 (1.0) | 161 (1.0) | 10 (1.6) | 8 (1.6) | 0.166 |
25–35 | 8300 (48.7) | 7703 (48.6) | 328 (50.2) | 269 (51.9) | |
> 35 | 8569 (50.2) | 8014 (50.4) | 315 (48.3) | 240 (46.5) | |
Race | |||||
White | 11,129 (69.4) | 10,384 (69.5) | 395 (65.8) | 350 (70.9) |
< 0.001
|
Black | 1015 (6.3) | 897 (6.0) | 57 (9.4) | 61 (12.3) | |
Hispanic | 1064 (6.6) | 960 (6.4) | 69 (11.5) | 35 (7.0) | |
Others | 2835 (17.6) | 2708 (18.1) | 79 (13.2) | 48 (9.7) | |
Missing | 1005 | 929 | 53 | 23 | |
Household income | |||||
Quartile1 | 1237 (7.3) | 1125 (7.2) | 63 (9.7) | 49 (9.5) |
< 0.001
|
Quartile2 | 2138 (12.7) | 1949 (12.4) | 112 (17.4) | 77 (15.1) | |
Quartile3 | 4111 (24.3) | 3775 (24.0) | 182 (28.1) | 154 (30.1) | |
Quartile4 | 9416 (55.7) | 8891 (56.5) | 291 (44.9) | 234 (45.3) | |
Missing | 146 | 138 | 5 | 3 | |
Primary Payer | |||||
Medicare/Medicaid | 767 (4.5) | 699 (4.4) | 36 (5.5) | 32 (6.2) | 0.153 |
Private including HMO | 15,661 (91.9) | 14,594 (91.9) | 595 (91.1) | 472 (91.3) | |
Self-pay/no-charge/other | 609 (3.6) | 574 (3.6) | 22 (3.4) | 13 (2.5) | |
Missing | 11 | 11 | 0 | 0 | |
Smoking | 642 (3.8) | 548 (3.5) | 57 (8.7) | 37 (7.1) |
< 0.001
|
PCOS | 682 (4.0) | 539 (3.4) | 69 (10.5) | 74 (14.3) |
< 0.001
|
Number of comorbidities
| |||||
0 | 12,449 (73.0) | 11,725 (73.8) | 433 (66.3) | 291 (56.3) |
< 0.001
|
1 ~ 2 | 4549 (26.7) | 4114 (25.9) | 216 (33.1) | 219 (42.3) | |
3+ | 50 (0.3) | 39 (0.2) | 4 (0.6) | 7 (1.4) | |
Comorbidities
| |||||
Coronary artery disease | 3 (0.0) | 2 (0.0) | 1 (0.2) | 0 (0.0) | - |
Congestive heart failure | 8 (0.0) | 6 (0.0) | 1 (0.2) | 1 (0.2) | 0.117 |
Diabetes | 211 (1.2) | 158 (1.0) | 20 (3.0) | 33 (6.4) |
< 0.001
|
Hypertension | 440 (2.6) | 335 (2.1) | 45 (6.9) | 60 (11.6) |
< 0.001
|
Cerebrovascular disease | 12 (0.1) | 12 (0.1) | 0 (0.0) | 0 (0.0) | - |
Chronic pulmonary disease | 859 (5.0) | 751 (4.7) | 54 (8.3) | 54 (10.4) |
< 0.001
|
Rheumatic disease | 94 (0.6) | 89 (0.6) | 3 (0.5) | 2 (0.4) | 0.844 |
Chronic kidney disease | 16 (0.1) | 15 (0.1) | 0 (0.0) | 1 (0.2) | - |
Coagulopathy | 690 (4.1) | 657 (4.1) | 22 (3.3) | 11 (2.1) |
0.047
|
Thyroid disorder | 2881 (16.9) | 2645 (16.7) | 118 (18.2) | 118 (22.8) |
< 0.001
|
Hospital information
| |||||
Hospital bed size | |||||
Small | 2340 (13.4) | 2184 (13.4) | 84 (12.8) | 72 (13.9) | 0.656 |
Medium | 4877 (28.8) | 4556 (28.9) | 171 (26.3) | 150 (29.0) | |
Large | 9816 (57.8) | 9124 (57.6) | 398 (61.0) | 294 (57.1) | |
Missing | 15 | 14 | 0 | 1 | |
Hospital location/teaching status | |||||
Rural | 462 (2.7) | 435 (2.7) | 12 (1.8) | 15 (2.9) |
0.030
|
Urban nonteaching | 3882 (22.7) | 3654 (22.9) | 126 (19.2) | 102 (19.7) | |
Urban teaching | 12,689 (74.6) | 11,775 (74.4) | 515 (79.0) | 399 (77.4) | |
Missing | 15 | 14 | 0 | 1 | |
Hospital region | |||||
Northeast | 5844 (34.5) | 5465 (34.6) | 206 (31.6) | 173 (33.6) | 0.095 |
Midwest | 2566 (15.0) | 2353 (14.8) | 118 (18.0) | 95 (18.3) | |
South | 4171 (24.3) | 3898 (24.4) | 145 (22.1) | 128 (24.6) | |
West | 4467 (26.2) | 4162 (26.2) | 184 (28.2) | 121 (23.5) |
Characteristics | Total (n = 17,048) | Maternal BMI, kg/m2 | P-value | ||
---|---|---|---|---|---|
< 30 (n = 15,878) | 30–39 (n = 653) | ≥ 40 (n = 517) | |||
Maternal outcomes
| |||||
Antepartum period | |||||
Pre-eclampsia and eclampsia | 1210 (7.1) | 1049 (6.6) | 79 (12.1) | 82 (15.9) |
< 0.001
|
Gestational diabetes | 850 (5.0) | 695 (4.4) | 71 (10.8) | 84 (16.3) |
< 0.001
|
Antepartum hemorrhage | 141 (0.8) | 138 (0.9) | 0 (0.0) | 3 (0.6) | - |
Placenta previa | 885 (5.2) | 833 (5.3) | 36 (5.5) | 16 (3.2) | 0.122 |
PPROM | 1444 (8.5) | 1347 (8.5) | 52 (7.9) | 45 (8.7) | 0.861 |
CAM | 201 (1.2) | 184 (1.2) | 12 (1.8) | 5 (1.0) | 0.259 |
Intrapartum period | |||||
Forceps | 133 (0.8) | 125 (0.8) | 4 (0.6) | 4 (0.8) | 0.858 |
Cesarean delivery | 8001 (46.9) | 7335 (46.2) | 349 (53.5) | 317 (61.4) |
< 0.001
|
Post-partum period | |||||
Post-partum hemorrhage | 1059 (6.2) | 979 (6.2) | 48 (7.4) | 32 (6.1) | 0.467 |
DIC | 61 (0.4) | 54 (0.3) | 1 (0.2) | 6 (1.2) |
0.009
|
VTE | 203 (1.2) | 189 (1.2) | 6 (0.9) | 8 (1.5) | 0.629 |
Post-partum hysterectomy | 3 (0.0) | 3 (0.0) | 0 (0.0) | 0 (0.0) | - |
Transfusion | 1 (0.0) | 1 (0.0) | 0 (0.0) | 0 (0.0) | - |
Hospital stay ≥ 6 days | 1208 (7.1) | 1085 (6.9) | 60 (9.2) | 63 (12.2) |
< 0.001
|
Fetal outcomes | |||||
Stillbirth and IUFD | 138 (0.8) | 124 (0.8) | 6 (0.9) | 8 (1.6) | 0.095 |
IUGR | 661 (3.9) | 615 (3.9) | 26 (4.0) | 20 (3.9) | 0.988 |
Premature birth | 1359 (8.0) | 1271 (8.0) | 51 (7.8) | 37 (7.2) | 0.791 |
LGA | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | - |
Birth defect | 300 (1.8) | 280 (1.8) | 13 (2.0) | 7 (1.4) | 0.754 |
Abortion | 118 (0.7) | 105 (0.7) | 9 (1.4) | 4 (0.8) | 0.085 |
Associations between BMI and maternal outcomes (BMI ≥ 40 and 30–39 versus < 30 kg/m2)
Variables | Univariate OR (95% CI) | Adjusted OR a (95% CI) | ||
---|---|---|---|---|
BMI 30–39 kg/m2 (vs. < 30 kg/m2) | BMI ≥ 40 kg/m2 (vs. < 30 kg/m2) | BMI 30–39 kg/m2 (vs. < 30 kg/m2) | BMI ≥ 40 kg/m2 (vs. < 30 kg/m2) | |
Maternal outcomes
| ||||
Antepartum period | ||||
Pre-eclampsia and eclampsia |
1.94 (1.51, 2.48)
|
2.67 (2.09, 3.42)
|
1.76 (1.35, 2.29)
|
2.25 (1.73, 2.94)
|
Gestational diabetes |
2.62 (2.02, 3.40)
|
4.23 (3.34, 5.36)
|
2.25 (1.70, 2.98)
|
3.64 (2.80, 4.72)
|
Placenta previa | 1.06 (0.75, 1.50) | 0.59 (0.35, 1.00) | 0.93 (0.64, 1.36) | 0.62 (0.36, 1.07) |
PPROM | 0.93 (0.70, 1.23) | 1.02 (0.75, 1.38) | 0.92 (0.68, 1.24) | 1.06 (0.77, 1.46) |
CAM | 1.59 (0.89, 2.84) | 0.83 (0.34, 2.02) | 1.40 (0.76, 2.58) | 0.81 (0.33, 1.98) |
Intrapartum period | ||||
Forceps | 0.77 (0.32, 1.84) | 0.99 (0.37, 2.68) | 0.88 (0.37, 2.10) | 1.12 (0.41, 3.11) |
Cesarean delivery |
1.34 (1.15, 1.57)
|
1.85 (1.55, 2.21)
|
1.36 (1.15, 1.60)
|
1.85 (1.54, 2.23)
|
Post-partum period | ||||
Post-partum hemorrhage | 1.21 (0.89, 1.63) | 0.99 (0.69, 1.43) | 1.14 (0.84, 1.56) | 0.99 (0.68, 1.45) |
DIC | 0.45 (0.06, 3.22) |
3.41 (1.37, 8.52)
| 0.47 (0.06, 3.51) |
3.79 (1.47, 9.78)
|
VTE | 0.78 (0.35, 1.74) | 1.30 (0.64, 2.63) | 0.79 (0.35, 1.77) | 1.20 (0.58, 2.47) |
Hospital stay ≥ 6 days |
1.38 (1.05, 1.80)
|
1.89 (1.44, 2.50)
| 1.19 (0.89, 1.59) |
1.60 (1.19, 2.14)
|
Associations between BMI and fetal outcomes (BMI ≥ 40 and 30–39 versus < 30 kg/m2)
Variables | Univariate OR (95% CI) | Adjusted OR a (95% CI) | ||
---|---|---|---|---|
BMI 30–39 kg/m2 (vs. < 30 kg/m2) | BMI 40 + kg/m2 (vs. < 30 kg/m2) | BMI 30–39 kg/m2 (vs. < 30 kg/m2) | BMI 40 + kg/m2 (vs. < 30 kg/m2) | |
Fetal outcomes
| ||||
Stillbirth and IUFD | 1.18 (0.59, 2.34) | 2.02 (0.99, 4.12) | 1.12 (0.56, 2.26) | 1.83 (0.88, 3.80) |
IUGR | 1.03 (0.70, 1.52) | 1.00 (0.64, 1.58) | 1.02 (0.68, 1.53) | 0.96 (0.61, 1.52) |
Premature birth | 0.97 (0.72, 1.30) | 0.89 (0.64, 1.24) | 0.89 (0.64, 1.23) | 0.86 (0.62, 1.21) |
Birth defect | 1.12 (0.65, 1.96) | 0.79 (0.37, 1.69) | 1.18 (0.68, 2.07) | 0.63 (0.28, 1.41) |
Abortion |
2.10 (1.10, 4.01)
| 1.18 (0.43, 3.21) | 1.88 (0.93, 3.78) | 1.13 (0.40, 3.17) |