Characteristic | Case1 | Control1 | Â | Â | Â | |||
---|---|---|---|---|---|---|---|---|
 |  | n | (%) | n | (%) | p | OR2 | (95% CI) |
Sex of index child3 | male | 130 | (67.0) | 38 | (63.3) | - | 1.0 | (ref) |
 | female | 64 | (33.0) | 22 | (36.7) | 0.60 | 0.47 | (0.47–1.56) |
Affected foot male | left | 26 | (25.0) | - | - | - | - | - |
 | right | 28 | (26.9) | - | - | - | - | - |
 | both | 50 | (48.1) | - | - | - | - | - |
Affected foot female | left | 6 | (12.8) | - | - | - | - | - |
 | right | 15 | (31.9) | - | - | - | - | - |
 | both | 26 | (55.3) | - | - | - | - | - |
Year of birth | 1963–1979 | 14 | (7.2) | 4 | (6.7) | - |  |  |
 | 1980–1989 | 32 | (16.5) | 15 | (25.0) | - |  |  |
 | 1990–1994 | 61 | (31.4) | 25 | (41.7) | - |  |  |
 | 1995–1999 | 87 | (44.8) | 16 | (26.7) | - |  |  |
Multiple pregnancy | yes | 10 | (5.1) | 0 | (0.0) | 0.07 | 3.244 | - |
 | no | 185 | (94.9) | 60 | (100) |  |  |  |
Type of delivery | Cephalic | 157 | (80.7) | 56 | (93.3) | - | 1.00 | (ref) |
 | Breech | 4 | (2.1) | 1 | (1.7) | 0.71 | 1.52 | (0.16–14.19) |
 | Caesarean | 33 | (17.2) | 3 | (5.0) | 0.04 | 3.71 | (1.09–12.62) |
Birth weight | mean | 3622 g | 3397 g | 0.105 | Â | - | Â | Â |
 | range | 1247–4564 g | 1531–4508 g | - | - | - |  |  |
Stillbirth6 |  | 5 | (2.6) | 1 | (1.7) |  | 1.77 | (0.20–15.81) |
Miscarriage6 |  | 50 | (25.8) | 15 | (25.4) |  | 1.04 | (0.53–2.03) |
Abortion6 |  | 33 | (17.2) | 9 | (15) |  | 1.14 | (0.51–2.56) |
Age of mother at birth of index child | ≤19 | 8 | (4.2) | 1 | (1.7) | 0.25 | 3.56 | (0.41–31.06) |
 | 20–24 | 39 | (20.2) | 12 | (20.0) | 0.53 | 1.25 | (0.55–2.83) |
 | 25–29 | 64 | (33.2) | 23 | (38.3) | - | 1.00 | (ref) |
 | 30–34 | 53 | (27.5) | 16 | (26.7) | 0.74 | 1.14 | (0.54–2.39) |
 | 35–39 | 23 | (11.9) | 7 | (11.7) | 0.79 | 1.14 | (0.43–3.03) |
 | ≥40 | 6 | (3.1) | 1 | (1.7) | 0.48 | 2.19 | (0.25–19.35) |
Age of father at birth of index child | ≤19 | 2 | (1.1) | 1 | (2.3) | 0.62 | 0.53 | (0.05–6.27) |
 | 20–24 | 20 | (11.4) | 5 | (11.4) | 0.87 | 1.10 | (0.36–3.40) |
 | 25–29 | 43 | (24.4) | 7 | (15.9) | 0.34 | 1.16 | (0.61–4.21) |
 | 30–34 | 63 | (35.8) | 17 | (38.6) | - | 1.00 | (ref) |
 | 35–39 | 31 | (17.6) | 10 | (22.7) | 0.60 | 0.78 | (0.31–1.94) |
 | ≥40 | 17 | (9.7) | 4 | (9.1) | 0.82 | 1.15 | (0.34–3.91) |
Rank of index pregnancy | 1 | 81 | (41.8) | 32 | (53.3) | - | 1.00 | (ref) |
 | 2 | 66 | (34.0) | 22 | (36.7) | 0.61 | 1.18 | (0.63–2.23) |
 | 3 | 27 | (13.9) | 4 | (6.7) | 0.10 | 2.60 | (0.84–8.05) |
 | 4+ | 20 | (10.3) | 2 | (3.3) | 0.09 | 3.67 | (0.81–16.74) |
Total gravidity of mother | 1 | 36 | (18.5) | 8 | (13.3) | - | 1.00 | (ref) |
 | 2 | 68 | (34.9) | 29 | (48.3) | 0.20 | 0.56 | (0.23–1.35) |
 | 3 | 48 | (24.6) | 13 | (21.7) | 0.72 | 0.83 | (0.31–2.23) |
 | 4+ | 43 | (22.1) | 10 | (16.7) | 0.90 | 1.07 | (0.37–3.05) |
Total parity of mother | 1 | 52 | (26.8) | 14 | (23.3) | - | 1.00 | (ref) |
 | 2 | 83 | (42.8) | 33 | (55.0) | 0.35 | 0.71 | (0.34–1.45) |
 | 3 | 38 | (19.6) | 10 | (16.7) | 0.88 | 1.08 | (0.43–2.71) |
 | 4+ | 21 | (10.8) | 3 | (5.0) | 0.28 | 2.15 | (0.54–8.47) |
Maternal use of folic acid in 3 months before or during first trimester of pregnancy with index child | no | 144 | (74.2) | 46 | (76.7) | - | 1.00 | (ref) |
 | yes | 50 | (25.8) | 14 | (23.3) | 0.67 | 0.86 | (0.43–1.73) |
Maternal smoking during pregnancy with index child | no | 129 | (66.5) | 44 | (73.3) | - | 1.00 | (ref) |
 | yes | 65 | (33.5) | 16 | (26.7) | 0.34 | 1.37 | (0.72–2.62) |
Paternal smoking during pregnancy with index child | no | 101 | (58.7) | 30 | (66.7) | - | 1.00 | (ref) |
 | yes | 71 | (41.3) | 15 | (33.3) | 0.29 | 1.46 | (0.72–2.95) |
Maternal alcohol consumption during pregnancy with index child | no | 127 | (65.5) | 34 | (56.7) | - | 1.00 | (ref) |
 | yes | 67 | (34.5) | 26 | (43.3) | 0.21 | 0.69 | (0.38–1.24) |
Maternal education or training beyond secondary school | no | 70 | (37.6) | 30 | (52.6) | - | 1.00 | (ref) |
 | yes | 116 | (62.4) | 27 | (47.4) | 0.09 | 1.71 | (0.93–3.16) |
Paternal education or training beyond secondary school | no | 52 | (31.3) | 12 | (27.3) | - | 1.00 | (ref) |
 | yes | 114 | (68.7) | 32 | (72.7) | 0.48 | 0.76 | (0.35–1.62) |