Using increases heart rate and constricts blood vessels causing dramatic elevations in blood pressure in both mother and foetus. This can result in numerous complications throughout all stages of foetal development. It may increase your chance of losing the baby before it is born, having the baby too early and/or other problems. Babies born to mothers who use during the pregnancy may weigh less and may get withdrawal symptoms from the drugs. Little is known about the long term effects on the child as it develops and grows.

For more information go to embryology.med.unsw.edu.au.