BMC Public Health 2007, 7:268 http://www.biomedcentral.com/1471-2458/7/268 Table 3: Pregnancy risk factors and relative risks (OR, 95% CI) of adverse pregnancy outcomes of women with insufficient antenatal care Pregnancy risk factors Study n, population Country Inadequate antenatal care Age < 18 Unmarried Multiparous (> 4) Unplanned pregnancy No health insurance Smoking Alcohol consumption Study n n, population Country Preterm birth Low birth weight Admission to NICU Fetal death Perinatal death Neonatal death Pregnancy outcome [9] 10382 two months national cohort, register data Jamaica 4% 1.7 (1.2–2.2)3 1.6 (1.1–2.2) 1.5 (0.9–2.4) 2.8 (1.6–4.7) 2.5 (1.8–3.4) 0.7 (0.5–0.9) [31] 85066 6 months hospital based cohort, clinical records (20 clinics) France 1.1% 2.8 (1.2–6.6)2 9.3 (6.0–14.3)1 34.9 (15.7–77.8)2 7.6 (2.2–26.8)2 [16] 21 722 Case- control, postpartum interview Ten European countries 5.9% 3.7 (2.7–5.1) 3.1 (2.5–3.9) 4.3 (3.1–6.0) 4.0 (3.3–4.7) 2.7 (2.1–3.4) [6] 344 Register based study (religional minority, national obstetric statistics) USA 3.6 (1.8–6.3) 2.7 (1.6–4.2) [32] 57108 One year national cohort, register data Finland 2.21 (1.95–2.51)2 2.05 (1.74–2.41)2 1.56 (1.24–1.98)2 1.87 (1.34–2.62)2 [31] 85066 6 months hospital based cohort, clinical records (20 clinics) France 5.8 (3.2–10.5)2 2.6 (1.5–4.4)2 2.8 (1.9–4.1) [8] 17765 two months cohort of nine maternity units, clinical records [18] 8065 one month cohort of six hospitals, clinical records England and Wales USA 7% 2.5 (2.0–3.0) 1.6 (1.4–1.9)2 10.2% 2.26 (1.76–2.90) 7.67 (5.96–9.86) Present study1 23 614 twelve years hospital based register data Finland 1.8% 1.29 (0.60–2.74) 1.88 (1.56–2.25) 2.03 (0.74–5.54) 4 1.87(1.39–2.52) 1.48(0.98–2.25) [18] 8065 one month cohort of six hospitals, clinical records USA 3.23 (2.62–3.99) 2.20 (1.72–2.79) 3.63 (2.23–5.91) Present study1 23 614 Mothers Under- Mothers Not- attending antenatal attending antenatal care care Finland 6.50 (4.71–8.99)2 6.62 (4.50–9.32)2 0.87 (0.52–1.44)2 7.75 (3.65–16.46)2 6.16 (4.70–9.32)2 4.60 (3.35–6.31)2 5.46 (3.90–7.65)2 1.18 (0.75–1.86)2 5.19 (2.04–13.22)2 8.66 (3.59–20.86)2 1Pooled, under-attending and non-attending 2OR adjusted for confounding factors found in the study; 3age under 20 years; = not applicable; 4over 7 births; 5number of visits relative to gestational length found to be important factors in the etiology of under- attending antenatal care [8], were not relevant in the present study. Preterm birth is an extremely heterogeneous index by which to assess obstetric outcome, because it combines a number of intrinsic pathways resulting in the same end- point [24]. Efforts to isolate these pathways would benefit from studying the individual components. In that regard, the substantially high incidence of placental abruption found in the present study is partly explained by smoking during pregnancy [25,26], but it also raises a hypothesis of trauma and domestic violence as possible explanations for adverse pregnancy outcome and a reduction in the uptake of services [27]. Amnionitis and neonatal deaths have been reported to be associated with a number of underlying risks, such as experienced violence during pregnancy and changing partners [28-30]. Overall, as failure to attend antenatal care is very rare in Finland, the underlying reasons probably varied and it can be assumed that women choosing to self exclude themselves from antenatal care have some serious but still poorly recognized problems, and difficulties in their over- all health behavior. This could partly explain the higher numbers of adverse pregnancy outcomes found in this study compared with earlier studies [6,18,31,32]. A strength of the present study is that we had the opportu- nity to assess the effects of maternal behavior and pre- pregnancy health on pregnancy outcomes, since the Kuo- pio University Hospital birth registry contains compre- Page 6 of 8 (page number not for citation purposes)