During pregnancy, the production of the DAO enzyme in the placenta increases, in order to create a metabolic barrier and to prevent the entrance of excessive histamine to the fetus. Studies show that the activity of the enzyme is between 500 and 1000 higher during pregnancy. This fact occurs to any woman, whether she has or not DAO deficiency.
The difference lies in those women that suffer from migraine or other typical symptoms of histamine accumulation, given that they notice a very relevant change. They go through a glorious stage during pregnancy: they do not have to use any drugs, do not have migraine crises and they feel good. This increase of the DAO enzyme starts between the second and third month of gestation and many women say that up until lactation they do not have any symptoms again.
Besides this great advantage of not suffering from migraine crisis, they do not have to worry that much about diet, because it does not need to be very low in histamine. My recommendation is to be careful with those foods that are richer in histamine, like canned food, hard-cheese and obviously alcoholic beverages, but other than that, they can have a normal lifestyle. During pregnancy there is no need to take DAO supplements if the symptoms have disappeared.
It has been studied that when the activity of the DAO enzyme remains low, and therefore there is an accumulation of histamine, there may be gestational complications. It can lead to premature rupture of the membranes, uterine tumors, and other disorders like diabetes, abortion and premature birth, although this is not usual. At any rate, it is important to control the levels of the enzyme during pregnancy, as well as the levels of histamine in plasma and urine. These three markers may be added to the protocols in the following years.