Are seasonal preferences in pregnancy planning a source of bias in studies of seasonal variation in reproductive outcomes?

1. Basso, O.
2. Olsen, J.
3. Bisanti, L.
4. Juul, S.
5. Boldsen, J.
6. Karmaus, W.
7. Olsen, J.
8. Fletcher, T.
9. Bolumar, F.
10. Figa-Talamanca, I.
11. Thonneau, P.
12. Pantelakis, S.