Table 1.
Characteristics of the study subjects with underweight pre-pregnancy BMI (severe, moderate, mild) and normal pre-pregnancy BMI.
| Underweight BMI categories (kg/m2) | ||||||
|---|---|---|---|---|---|---|
| Variable | Severe (<16) N=4665 |
Moderate (16–16.9) N=11108 |
Mild (17–18.49) N=56913 |
Normal (18.5–24.9) N=877670 |
P-value* | |
| Maternal age in years (SD) | 25.2 (6.1) | 25.8 (6.2) | 26.9 (6.5) | 28.1 (6.4) | <0.001 | |
| Maternal height in inches (SD) | 66.0 (4.1) | 64.7 (3.1) | 64.2 (2.8) | 63.7 (2.7) | <0.001 | |
| Maternal | <0.001 | |||||
| race/ethnicity: | ||||||
| Non-Hispanic White | 21% (968) | 26% (2882) | 30% (16919) | 32% (279545) | ||
| Non-Hispanic Black | 6% (265) | 6% (706) | 5% (3050) | 5% (41730) | ||
| Asian | 24%(1100) | 24% (2693) | 26% (14543) | 14% (118945) | ||
| Hispanic | 45%(2118) | 38% (4268) | 35% (19908) | 45% (398216) | ||
| Other | 5% (214) | 5% (559) | 4% (2493) | 4% (39234) | ||
| Maternal education: | <0.001 | |||||
| Some high school or less | 31% (1459) | 25% (2725) | 21% (11956) | 22% (195074) | ||
| High school graduate | 29% (1375) | 29% (3224) | 25% (14387) | 24% (210910) | ||
| Some college | 20% (946) | 22% (2484) | 22% (12347) | 22% (191438) | ||
| College graduate or more | 19% (885) | 24% (2675) | 32% (18223) | 32% (280248) | ||
| Parity: | <0.001 | |||||
| 1 | 58% (2691) | 56% (6237) | 55% (31169) | 46% (402570) | ||
| ≥2 | 42% (1974) | 44% (4871) | 45% (25744) | 54% (475100) | ||
| Prenatal care initiation: | <0.001 | |||||
| In first 5 months | 91% (4265) | 92% (10194) | 93% (53100) | 94% (825314) | ||
| 6 months or later/no initiation/unknown | 9% (400) | 8% (914) | 7% (3813) | 6% (52356) | ||
| Payer for prenatal care: | ||||||
| MediCal (Public) | 59% (2738) | 50% (5598) | 44% (24790) | 42% (367834) | <0.001 | |
| Private | 34% (1590) | 43% (4789) | 51% (28754) | 53% (464187) | ||
| NA/Uninsured/Unknown | 4% (192) | 3% (367) | 3% (1672) | 2% (19493) | ||
| Other | 3% (145) | 3% (354) | 3% (1697) | 3% (26156) | ||
| Prior preterm delivery at <37 weeks: | 0.285 | |||||
| No | 99% (4637) | 99% (11034) | 99% (56,602) | 99% (872956) | ||
| Yes | 1% (28) | 1% (74) | 1% (311) | 1% (4714) | ||
| Preterm delivery (<37 weeks): | <0.001 | |||||
| Spontaneous | 8% (350) | 7% (734) | 6% (3264) | 5% (42670) | ||
| Medically indicated | 2% (84) | 2% (176) | 1% (724) | 1% (10283) | ||
| Unclassified | 1% (41) | 1% (91) | 1% (433) | 1% (5191) | ||
BMI, body mass index
Data are presented as mean (SD) for maternal age and height, and % (N) for all the other variables
*
ANOVA or Chi-square test used for comparison.