This is actually a very common phenomenon during pregnancy. Many women find they experience an improvement in lactose tolerance when they get pregnant and, for some, this ability to digest lactose remains after they deliver, but for others their lactose intolerance returns or even becomes worse. Healthcare professionals often talk about a "rule of thirds" during pregnancy. The "rule of thirds" means that approximately one third of pregnant women will see an improvement in their symptoms, one third will remain the same, and one third will see their symptoms worsen. This rule of thirds can occur with many conditions, including: migraine headaches, eczema, asthma and lactose intolerance. Researchers still don't completely understand why this happens, although some attribute it to hormonal changes during pregnancy.
Joanne Saab, RD is a registered dietitian who practices in pediatrics at McMaster Children's Hospital in Hamilton, Ontario. Joanne is co-author of three books in conjunction with the Hospital for Sick Children: Better Food for Kids, Better Food for Pregnancy and the best-selling Better Baby Food. Joanne also enjoys being the mother to twin daughters who have taught her a lot of practical know-how on kids' nutrition.