1. Effects of pregnancy on work performance. Council on Scientific Affairs
2. Commission of the European Communities. 1992. On the implementation of Council directive 92/85/EEC of 19 October on the introduction of measures to encourage improvements in the health and safety at work of pregnant workers and workers who have recently given birth or are breastfeeding. Brussels, 15.03.1999, COM (1999)100 final_
3. Cunningham, F. G., Leveno, K. J.MacDonald, P. C. 1997.Williams Obstetrics,, 20th edition, 240Norwalk, CT: Appleton & Lange. (