- Abstract Nitrogen Dioxide (NO 2 ) is a product of fuel combustion originating mainly from industry and transportation. Studies suggest an association between NO 2 and congenital malformations (CM). We investigated an independent effect of NO 2 on CM by adjusting to individual factors and household environment in 1024 Bedouin-Arab pregnant women in southern Israel. This population is characterised by high rates of CMs, frequent consanguineous marriages, paternal smoking, temporary housing and usage of open fire for heat cooking. Information on household risk factors was collected during an interview. Ambient measurements of 24-h average NO 2 and meteorological conditions were obtained from 13 local monitors. Median value of daily NO 2 measured in the area was 6.78 ppb. CM was diagnosed in 8.0% (82) of offspring. Maternal NO 2 exposure during the 1st trimester >8.6 ppb was significantly associated with minor CM (RR = 2.68, p = 0.029). Major CM were independently associated with maternal juvenile diabetes (RR = 9.97, p -value = 0.002) and heating by open fire (RR = 2.00, p -value = 0.049), but not NO 2 exposure. We found that NO 2 emissions had an independent impact only on minor malformations, whereas major malformations depended mostly on the household environment. Antepartum deaths were associated by maternal morbidity.