At first it is best to try increasing the fibre in your diet and increasing the amount of non-alcoholic fluids that you drink.

http://www.patient.co.uk/health/planning-to-become-pregnant

Laxatives. Constipation is common in pregnancy and you may need a laxative. At first it is best to try increasing the fibre in your diet and increasing the amount of non-alcoholic fluids that you drink.