Appendix Table 2.
Prenatal and Baseline Characteristics of Women With GDM, by Lactation Intensity Groups at 6 to 9 wk After Delivery (Study Baseline)*
| Characteristic | Exclusive Formula (n = 153) |
Mostly Formula, Mixed/Inconsistent (n = 214) |
Mostly Lactation (n = 387) |
Exclusive Lactation (n = 205) |
|---|---|---|---|---|
| Sociodemographic | ||||
| Mean age at baseline (SD), y | 33.0 (4.9) | 33.4 (5.0) | 33.4 (4.8) | 33.5 (4.4) |
| Education, n (%)† | ||||
| High school or less | 60 (39.2) | 56 (26.2) | 79 (20.4) | 35 (17.1) |
| Some college | 55 (36.0) | 55 (25.7) | 106 (27.4) | 54 (26.3) |
| College graduate | 38 (24.8) | 103 (48.1) | 202 (52.2) | 116 (56.6) |
| Race/ethnicity, n (%)†‡ | ||||
| Non-Hispanic white | 34 (22.2) | 43 (20.1) | 79 (20.4) | 69 (33.6) |
| Non-Hispanic black | 22 (14.4) | 19 (8.9) | 20 (5.2) | 11 (5.4) |
| Hispanic | 48 (31.4) | 68 (31.8) | 118 (30.5) | 58 (28.3) |
| Asian | 43 (28.1) | 80 (37.3) | 166 (42.9) | 63 (30.7) |
| Other | 6 (3.9) | 4 (1.9) | 4 (1.0) | 4 (2.0) |
| Parity, n (%) | ||||
| Primiparous | 49 (32.0) | 93 (43.5) | 132 (34.1) | 72 (35.1) |
| Multiparous | 104 (68.0) | 121 (56.5) | 255 (65.9) | 133 (64.9) |
| Polycystic ovarian syndrome, n (%) | 10 (6.5) | 11 (5.1) | 31 (8.0) | 10 (4.9) |
| WIC recipient, n (%)† | 59 (38.6) | 55 (25.7) | 87 (22.5) | 45 (22.0) |
| Family history of diabetes, n (%) | 70 (45.8) | 103 (48.1) | 204 (52.7) | 96 (46.8) |
| Prenatal | ||||
| Mean prepregnancy BMI (SD), kg/m2† | 31.2 (8.3) | 30.0 (7.8) | 29.3 (6.7) | 28.3 (6.1) |
| Prepregnancy weight status, n (%)§ | ||||
| BMI <25 kg/m2 | 38 (24.8) | 66 (30.8) | 114 (29.5) | 73 (35.6) |
| BMI 25 of <30 kg/m2 | 37 (24.2) | 60 (28.0) | 125 (32.3) | 65 (31.7) |
| BMI ≥30 kg/m2 | 78 (51.0) | 88 (41.2) | 148 (38.2) | 67 (32.7) |
| Mean gestational weight gain (SD), kg | 10.8 (7.9) | 10.2 (6.5) | 10.2 (6.5) | 10.3 (6.9) |
| Mean 3-h, 100-g OGTT (SD), mg/dL | ||||
| Fasting glucose level | 92.2 (11.4) | 93.4 (11.1) | 92.0 (12.6) | 90.4 (12.8) |
| 1-h glucose level | 199.0 (22.1) | 201.3 (23.0) | 198.6 (23.2) | 199.1 (23.1) |
| 2-h glucose level | 177.1 (25.0) | 176.3 (28.8) | 176.0 (29.2) | 176.7 (24.7) |
| 3-h glucose level | 126.3 (34.7) | 128.5 (31.1) | 127.8 (33.3) | 122.7 (33.7) |
| Mean sum of 3-h OGTT Z scores (SD) | 0.0 (2.3) | 0.3 (2.6) | 0.0 (2.8) | −0.2 (2.6) |
| Median sum of 3-h OGTT Z scores (IQR) | −0.3 (−1.6 to 1.3) | −0.3 (−1.5 to 1.4) | −0.6 (−1.8 to 1.3) | −0.7 (−1.9 to 0.7) |
| Mean gestational age at GDM diagnosis (SD), wk | 24.9 (7.8) | 24.9 (7.2) | 25.4 (6.9) | 26.4 (6.5) |
| Treatment of GDM, n (%)‡ | ||||
| Diet modification only | 108 (70.6) | 141 (65.9) | 263 (68.0) | 143 (69.8) |
| Oral hypoglycemic agents | 43 (28.1) | 65 (30.4) | 105 (27.1) | 57 (27.8) |
| Insulin | 2 (1.3) | 8 (3.7) | 19 (4.9) | 5 (2.4) |
| Hospital labor and delivery | ||||
| Mean length of gestation (SD), wk‖ | 39.0 (1.1) | 39.3 (1.1) | 38.9 (1.2) | 39.2 (1.0) |
| Mean length of stay (SD), d† | 2.6 (1.1) | 2.8 (1.3) | 2.5 (1.0) | 2.3 (0.9) |
| Cesarean section, n (%)§ | 61 (39.9) | 74 (34.6) | 113 (29.2) | 57 (27.8) |
| 6 to 9 wk after delivery (baseline) | ||||
| Mean BMI (SD), kg/m2† | 32.0 (7.7) | 30.6 (7.1) | 29.8 (6.4) | 28.5 (5.2) |
| Mean waist circumference (SD), cm† | 93.6 (14.9) | 91.5 (15.8) | 89.1 (13.1) | 86.9 (11.0) |
| Mean weight change postdelivery (SD), kg | −8.9 (4.0) | −8.7 (3.7) | −9.1 (3.6) | −9.5 (3.4) |
| Mean HOMA-IR index score (SD)† | 7.0 (4.1) | 6.5 (5.1) | 4.9 (3.2) | 4.3 (2.8) |
| Median HOMA-IR index score (IQR)† | 5.9 (4.0–8.7) | 5.1 (3.1–8.5) | 4.1 (2.7–6.3) | 3.5 (2.6–5.1) |
| Mean 2-h, 75-g OGTT results (SD) | ||||
| Fasting glucose level, mg/dL† | 97.8 (9.1) | 97.3 (10.2) | 93.2 (8.0) | 92.2 (7.9) |
| 2-h postload glucose level, mg/dL† | 110.6 (25.8) | 117.4 (27.6) | 113.0 (28.5) | 106.9 (28.4) |
| Mean 2-h, 75-g OGTT results (SD) | ||||
| Fasting glucose level, mmol/L† | 5.4 (0.5) | 5.4 (0.6) | 5.1 (0.4) | 5.1 (0.4) |
| 2-h postload glucose level, mmol/L† | 6.1 (1.4) | 6.5 (1.5) | 6.2 (1.6) | 5.9 (1.6) |
| Glucose tolerance, n (%)† | ||||
| Normal | 89 (58.2) | 119 (55.6) | 265 (68.5) | 155 (75.6) |
| IFG level only | 43 (28.1) | 53 (24.8) | 53 (13.7) | 27 (13.2) |
| IGT only | 9 (5.9) | 20 (9.3) | 50 (12.9) | 16 (7.8) |
| IFG level and IGT | 12 (7.8) | 22 (10.3) | 19 (4.9) | 7 (3.4) |
| Depression, n (%) | ||||
| None | 126 (86.3) | 174 (84.5) | 325 (86.0) | 176 (88.9) |
| Moderate or severe | 20 (13.7) | 32 (15.5) | 53 (14.0) | 22 (11.1) |
| Median lifestyle behaviors (IQR) | ||||
| Total PA, metabolic equivalent h/wk§ | 46.5 (35.4–61.1) | 41.8 (32.2–59.4) | 42.8 (30.4–54.6) | 42.9 (31.3–54.1) |
| Moderate to vigorous PA, metabolic equivalent h/wk | 24.3 (16.2–35.6) | 22.0 (14.3–33.5) | 21.5 (13.7–30.3) | 20.5 (13.5–29.7) |
| Glycemic index† | 186.5 (136.4–375.2) | 223.6 (166.5–280.3) | 232.5 (177.7–313.1) | 248.9 (186.4–337.5) |
| Dietary fiber, g/100 kcal† | 0.9 (0.7–1.1) | 1.0 (0.8–1.2) | 1.0 (0.8–1.3) | 1.1 (0.8–1.3) |
| Dietary animal fat, percentage of kcal† | 28.4 (18.8–33.5) | 25.8 (19.4–31.3) | 24.4 (18.9–30.3) | 24.2 (19.5–29.4) |
| Contraception methods, n (%)‡ | ||||
| Progesterone only | 8 (5.2) | 4 (1.9) | 10 (2.6) | 4 (2.0) |
| Combination oral pills | 24 (15.7) | 20 (9.4) | 46 (11.9) | 28 (13.7) |
| Intrauterine device | 17 (11.1) | 18 (8.3) | 41 (10.6) | 15 (7.3) |
| None/barrier | 104 (68.0) | 172 (80.4) | 290 (74.9) | 158 (77.0) |
| Subsequent birth (1 birth during 2-y follow-up), n (%) | 16 (10.5) | 32 (15.0) | 44 (11.4) | 22 (10.7) |
BMI = body mass index; GDM = gestational diabetes mellitus; HOMA-IR = Homeostatic Metabolic Assessment of Insulin Resistance; IFG = impaired fasting glucose; IGT = impaired glucose tolerance; IQR = interquartile range; OGTT = oral glucose tolerance test; PA = physical activity; sum of 3-h OGTT Z scores = sum of the 4 Z scores for the prenatal 100-g OGTT glucose values (fasting and 1, 2, and 3 h); WIC = Special Supplemental Nutrition Program for Women, Infants, and Children (eligibility based on income ≤185% of the federal poverty level).
*
Chi-square test for categorical variables; t test or analysis of variance for continuous variables. Kruskal–Wallis test to compare medians. Data were missing for depression score (n = 31), HOMA-IR index score (n = 5), and lifestyle behaviors (n = 5).
†
P < 0.001.
‡
Fisher exact test for cell sizes <5. Two-sided P values.
§
P < 0.050.
‖
P < 0.010.