Not only should pregnant women refrain from diving, women who think they may be pregnant or are trying to become pregnant should likewise avoid it. A survey of 208 mothers who dived during pregnancy showed higher rates of low birth weight, birth defects, neonatal respiratory difficulties and other problems
Here are two links for information from Divers Alert Network on the risks of pregnancy and diving:
https://www.diversalertnetwork.org/medical/articles/The_Risks_of_Pregnancy_and_Diving
http://www.alertdiver.com/womens_health_and_diving