Table 1.
Demographic and Clinical Characteristics by Duration of Any Breastfeeding for the Index Pregnancy
| Characteristics | Never (n=509) | <1 mo (n=317) | 1 to <3 mo (n=428) | 3 to <6 mo (n=653) | 6 to <9 mo (n=651) | 9+ mo (n=1040) | P value |
|---|---|---|---|---|---|---|---|
| Maternal age at birth of index child, mean (SD), y | 28.2 (4.6) | 28.7 (4.7) | 28.7 (4.3) | 29.7 (4.2) | 30.1 (4.0) | 31.3 (4.1) | <0.001 |
| Race, n (%) | |||||||
| White | 496 (97.5) | 308 (97.2) | 418 | 629 (96.3) | 626 (96.2) | 1008 (96.9) | 0.233 |
| Black | <5 | <5 | (97.7) | 5 (0.8) | 9 (1.4) | 8 (0.8) | |
| Other | <5 | 5 (1.6) | <5 | 10 (1.5) | 7 (1.1) | 17 (1.6) | |
| Missing | 6 (1.2) | <5 | <57 (1.6) | 9 (1.4) | 9 (1.4) | 7 (0.7) | |
| Married, n (%) | |||||||
| No | 89 (17.5) | 44 (13.9) | 62 (14.5) | 115 (17.6) | 73 (11.2) | 147 (14.1) | 0.034 |
| Yes | 415 (81.5) | 271 (85.5) | 363 (84.8) | 537 (82.2) | 572 (87.9) | 882 (84.8) | |
| Missing | 5 (1.0) | <5 | <5 | <5 | 6 (0.9) | 11 (1.1) | |
| Manual social class, n (%) | |||||||
| No | 337 (66.2) | 232 (73.2) | 313 (73.1) | 484 (74.1) | 529 (81.3) | 774 (74.4) | 0.001 |
| Yes | 120 (23.6) | 50 (15.8) | 75 (17.5) | 99 (15.2) | 67 (10.3) | 147 (14.1) | |
| Missing | 52 (10.2) | 35 (11.0) | 40 (9.4) | 70 (10.7) | 55 (8.5) | 119 (11.4) | |
| University‐level education, n (%) | |||||||
| No | 485 (95.3) | 292 (92.1) | 376 (87.9) | 542 (83.0) | 464 (71.3) | 698 (67.1) | 0.001 |
| Yes | 18 (3.5) | 20 (6.3) | 46 (10.8) | 106 (16.2) | 182 (28.0) | 335 (32.2) | |
| Missing | 6 (1.2) | 5 (1.6) | 6 (1.4) | 5 (0.8) | 5 (0.8) | 7 (0.7) | |
| Prepregnancy BMI, mean (SD), kg/m2 | 23.3 (4.0) | 22.8 (3.6) | 22.8 (3.6) | 22.4 (3.3) | 22.1 (2.9) | 22.0 (2.9) | <0.001 |
| Primigravid, n (%) | |||||||
| No | 348 (68.4) | 179 (56.5) | 258 (60.3) | 378 (57.9) | 395 (60.7) | 734 (70.6) | <0.001 |
| Yes | 158 (31.0) | 137 (43.22) | 166 (38.8) | 267 (41.0) | 253 (38.9) | 300 (28.9) | |
| Missing | <5 | <5 | <5 | 8 (1.2) | <5 | 6 (0.6) | |
| Smoking at recruitment, n (%) | |||||||
| No | 386 (75.8) | 262 (82.7) | 346 (80.8) | 542 (83.0) | 585 (89.9) | 934 (89.8) | <0.001 |
| Yes | 121 (23.8) | 54 (17.0) | 78 (18.2) | 103 (15.8) | 61 (9.4) | 93 (8.9) | |
| Missing | <5 | <5 | <5 | 8 (1.2) | 5 (0.8) | 13 (1.3) | |
| Pregnancy diabetes, n (%) | |||||||
| None | 486 (95.5) | 303 (95.6) | 411 (96.0) | 626 (95.9) | 630 (96.8) | 1004 (96.5) | 0.904 |
| GD | 5 (1.0) | <5 | <5 | <5 | <5 | 5 (0.5) | |
| Pre‐GD | <5 | <5 | <5 | <5 | <5 | <5 | |
| Glycosuria | 16 (3.1) | 11 (3.47) | 12 (2.8) | 23 (3.5) | 18 (2.8) | 27 (2.6) | |
| HDP, n (%) | |||||||
| None | 416 (81.7) | 270 (85.2) | 350 (81.8) | 569 (87.1) | 551 (84.6) | 913 (87.8) | 0.001 |
| Gestational hypertension | 79 (15.5) | 42 (13.3) | 60 (14.0) | 74 (11.3) | 87 (13.4) | 114 (11.0) | |
| Preeclampsia | 14 (2.7) | 5 (1.58) | 18 (4.2) | 10 (1.5) | 13 (2.0) | 13 (1.3) | |
| Preterm birth, n (%) | |||||||
| No | 486 (95.5) | 296 (93.4) | 415 (97.0) | 629 (96.3) | 621 (95.4) | 1007 (96.8) | 0.169 |
| Yes | 23 (4.5) | 21 (6.6) | 13 (3.0) | 24 (3.7) | 30 (4.6) | 33 (3.2) | |
| Follow‐up measures | |||||||
| Maternal age, mean (SD), y | 46.6 (4.5) | 46.9 (4.5) | 47.1 (4.2) | 48.0 (4.2) | 48.4 (4.0) | 49.6 (4.1) | <0.001 |
| Medication usage, n (%) | |||||||
| Antihypertensives | 38 (7.47) | 14 (4.42) | 20 (4.67) | 29 (4.44) | 23 (3.53) | 46 (4.42) | |
| Cholesterol‐lowering agents | 10 (1.96) | <5 | 6 (1.40) | 11 (1.68) | 11 (1.69) | 12 (1.15) | |
| Diabetes medications | 10 (1.96) | <5 | 5 (1.17) | <5 | 6 (0.92) | 12 (1.15) | |
Categories with cell counts with <5 participants are designated as N<5 per Avon Longitudinal Study of Parents and Children policy to protect participant anonymity. BMI indicates body mass index; GD, gestational diabetes; and HDP, hypertensive disorders of pregnancy.