| Mean | SD | N | % |
---|---|---|---|---|
Age (years) | 16.1 | 0.81 | Â | Â |
Body Mass Index (kg/m 2 ) | 19.9 | 3.09 | Â | Â |
Weeks of Gestation a | 39.2 | 2.37 | Â | Â |
Breastfeeding duration of index son (weeks) b | 36.9 | 25.2 | Â | Â |
Prior maternal breastfeeding (weeks) b | 18.1 | 38.3 | Â | Â |
Birth weight (gm) c | 3433 | 439 | Â | Â |
Current residential distance to Khimprom factory (km) | 4.45 | 1.76 | Â | Â |
Time boy resided in Chapaevsk(yrs) | 14.0 | 3.70 | Â | Â |
Gravidity d | Â | Â | Â | Â |
0 | Â | Â | 14 | 48 |
1 | Â | Â | 8 | 28 |
2–3 |  |  | 7 | 24 |
Parity d | Â | Â | Â | Â |
0 | Â | Â | 17 | 59 |
1 | Â | Â | 10 | 34 |
2–3 |  |  | 2 | 7 |
Monthly family income level | Â | Â | Â | Â |
   300–1000 rubles ($10–$35 U.S.) |  |  | 8 | 28 |
   1000–1500 rubles ($35–$50 U.S.) |  |  | 7 | 24 |
   >1500 rubles (> $50 U.S.) |  |  | 14 | 48 |
Maximum parental education level | Â | Â | Â | Â |
8–11 th grade |  |  | 2 | 7 |
Junior College | Â | Â | 17 | 59 |
University | Â | Â | 8 | 28 |