VITAMIN-A AND BIRTH-DEFECTS

OBJECTIVE: Our objective was to determine whether moderate doses of vi tamin A are teratogenic. STUDY DESIGN: This was a geographically based case-control study. Women whose pregnancies produced offspring with n eural tube defects (n = 548) or major malformations other than neural tube defects (n = 387) and normal control subjects (n = 573) were inte rviewed to determine periconceptional vitamin A supplement exposure le vels. RESULTS: The proportion of;women consuming doses of vitamin A be tween 8000 and 25,000 IU was no greater in the major malformations gro up or the group with neural tube defects than in the normal control gr oup. For exposure from supplements and fortified cereals combined, wom en consuming >8000 and >10,000 IU daily had odds ratios for major malf ormations of 0.79 (95% confidence Interval 0.40 to 1.53) and 0.73 (95% confidence interval 0.27 to 1.96), respectively, compared with women consuming <5000 IU. The results for neural tube defects were similar. For cranial neural crest defects the odds ratios were 0.76 (0.22 to 2. 56) and 1.09 (0.24 to 4.98) for exposure to >8000 and >10,000 IU, resp ectively, versus exposure to <5000 IU. CONCLUSIONS: This study found n o association between periconceptional vitamin A exposure at doses >80 00 IU or >10,000 IU per day and malformations in general, cranial neur al crest defects, or neural tube defects. If vitamin A is a teratogen, the minimum teratogenic dose appears to be well above the level consu med by most women during organogenesis.