Table 1.
Characteristics and corresponding sex ratios (male/female) for women delivering a liveborn singleton at Kaiser Permanente Northern California, 1996–2008
| n (%) | Sex ratio | P * | |
|---|---|---|---|
| All women | 288 009 | 1.05 | |
| Age (years) | 0.85 | ||
| 15–19 | 22 214 (7.7) | 1.03 | |
| 20–24 | 53 876 (18.7) | 1.05 | |
| 25–29 | 83 698 (29.1) | 1.05 | |
| 30–34 | 77 685 (27.0) | 1.05 | |
| 35–39 | 40 580 (14.1) | 1.06 | |
| 40–45 | 9956 (3.5) | 1.05 | |
| Parity† (n = 287 790) | 0.87 | ||
| 0 | 166 756 (57.9) | 1.05 | |
| 1 | 71 677 (24.9) | 1.04 | |
| 2 | 33 437 (11.6) | 1.05 | |
| 3+ | 15 920 (5.5) | 1.04 | |
| Education† (n = 282 527) | 0.27 | ||
| Elementary or secondary school only | 34 785 (12.3) | 1.04 | |
| High school graduate | 79 188 (28.0) | 1.04 | |
| Some college | 79 923 (28.3) | 1.06 | |
| College graduate | 50 985 (18.1) | 1.06 | |
| Graduate studies | 37 646 (13.3) | 1.04 | |
| Race–ethnicity† (n = 285 529) | 0.05 | ||
| Non-Hispanic Caucasian | 114 838 (40.2) | 1.05 | |
| Hispanic | 83 009 (29.1) | 1.04 | |
| African American | 24 256 (8.5) | 1.02 | |
| Asian | 62 284 (21.8) | 1.07 | |
| Other | 1142 (0.4) | 1.10 | |
| Year of delivery | 0.18 | ||
| 1996–1997 | 51 309 (17.8) | 1.04 | |
| 1998–1999 | 47 462 (16.5) | 1.03 | |
| 2000–2001 | 42 258 (14.7) | 1.05 | |
| 2002–2003 | 43 087 (15.0) | 1.05 | |
| 2004–2005 | 40 449 (14.0) | 1.04 | |
| 2006–2007 | 42 553 (14.8) | 1.07 | |
| 2008 | 20 891 (7.3) | 1.06 |
*
χ2 test of independence for variable of interest and infant sex.
†
n differs because of missing values.