Delving into some family history may help an expectant mother—and her healthcare providers—know what to expect during her pregnancy. While every pregnancy differs, some conditions and complications tend to run in families. For example, the intensity of a woman’s morning sickness or the likelihood of her having fraternal twins may have a hereditary basis.
Although prenatal care is designed to monitor a range of potential problems, discussing family history is an important part of a comprehensive care plan.
Here are a few conditions that have a hereditary basis:
- Morning sickness
An estimated 50 percent of women experience morning sickness during the first trimester and for some the problem is so severe that it interferes with the ability to eat enough and extreme morning sickness may even continue into subsequent trimesters. Serious morning sickness occurs in less than two percent of all pregnancies but can lead to vitamin and nutritional deficiencies if not treated. Data collected by the Norwegian Institute of Public Health found that women are more likely to suffer from severe morning sickness if their mother did. The risk did not increase if the father’s mother experienced it.
- Gestational diabetes
About 2 to 5 percent of all pregnant women develop gestational diabetes. This type of diabetes develops during pregnancy due to hormonal changes that increase insulin resistance and lead to high blood sugar. A variety of factors—including the woman’s own health—are implicated but studies show that some women may be predisposed to develop diabetes. Tests for gestational diabetes are part of prenatal care. If an expectant mother does have gestational diabetes, she will require more-frequent checkups and need to manage her blood sugar. In most cases, a woman’s blood sugar will return to normal after the baby is born.
- Bigger babies
How much a mother weighs and what she eats during pregnancy will both have an effect on her baby’s birth weight, but some studies suggest that genes can help determine the size of a newborn. Surprisingly, it’s not only the mother’s genes that count. A study led by Britain’s UCL Institute of Child Health found genes inherited from both the mother and father may each regulate the baby’s growth at different points in the pregnancy.
- Twins: Identical and fraternal
Twins do seem to run in families, although it is more likely to happen with fraternal or non identical twins. Data from 2000 mothers of fraternal twins showed that two particular genes increase a woman’s chance of having fraternal twins. One gene affects hormone levels and how many eggs the ovaries release during a menstrual cycle. Having both genes increases a mother’s chances of twins by 29%. If a woman’s mother, sister or aunt had fraternal twins, it’s likely that she has a higher than average chance of continuing the family tradition.
- Early labor
Early labor—defined as labor that happens before the 37th week of pregnancy—may be caused by a variety of factors, including the baby’s genes. A 2015 study by the Eunice Kennedy Shriver Genomics and Proteomics Network for Preterm Birth Research found a significant increase in preterm births—before 34 weeks of pregnancy—among babies in whom any of four implicated genes were duplicated or any of seven genes were deleted. The findings may lead to a screening test to help identify babies at a higher risk for preterm birth.
Prenatal visits include taking your blood pressure—and there’s a good reason for that. It’s an easy way to screen for high or erratic blood pressure, a symptom of preeclampsia. About 1 in 200 women develop this condition during pregnancy. Preeclampsia can progress into life-threatening complications for both mother and child but it is treatable once diagnosed. Some studies suggest that the father’s genes rather than the mother’s are implicated in a higher risk for preeclampsia. If the father’s mother or sister had preeclampsia, expectant parents should inform their healthcare provider.
No one is sure what causes intrahepatic cholestasis of pregnancy (ICP), a rare condition which affects approximately one percent of all pregnancies in the U.S. The liver disease, which only happens during pregnancy, may be caused by a mixture of genetic, hormonal, and environmental factors. About 15 percent of women who have mutations in certain genes will develop the condition and those genes can be passed on. If a woman’s mother or sister had ICP, she should let healthcare provider know. The symptoms—including severe itching—usually go away after delivery.
- Blood clots and deep vein thrombosis
Obesity, a tendency toward blood clots, being pregnant at an older age, and leading an inactive life can all increase the danger of blood clots and deep vein thrombosis during pregnancy, but genetic variations also increase the likelihood. Research found that women with certain genetic variations are more likely to have such circulation issues early on in their pregnancy.
Melasma—the skin discoloration women experience during pregnancy—is due to hormonal changes but some women may be predisposed to this form of hyperpigmentation. Although discoloration may be worsened by environmental factors, such as sun exposure, hyperpigmentation tends to run in families. Fortunately, the discoloration usually fades after the child’s birth.
Asking both sides of the family about their experiences during pregnancy—and any problems they faced—can help an expectant mother better cope with possible hereditary conditions.