By Sonia Alvarado, CTIS Pregnancy Health Information Line Counselor
Since March is National Kidney month, it’s a good time to learn a little about prenatal exposure to drugs as well as maternal diseases that can have an effect on function and development of the fetal kidney.
Although there are a number of conditions that affect the kidney, there are generally two major causes that need to be considered in pregnancy: diabetes and hypertension. Experts worry that the growing number of obese individuals, including women of reproductive age, will mean more diabetes. Diabetes affects kidney function, One of the major categories of drugs used to treat kidney disease in diabetic women as well as others are called angiotensin-converting enzyme (ACE) inhibitors. Unfortunately this group of drugs can cause serious kidney damage in the developing fetus when exposure occurs in the second or third trimester of pregnancy. These drugs are associated with oligohydramnios and anhydramnios (low or no amniotic fluid) and stillbirth, both the result of damage to the developing kidney.
Hypertension is another condition that is associated with chronic kidney disease (CKD) and kidney failure. CKD as well as first pregnancy, genetic factors, and twin pregnancy are risk factors for the development of preeclampsia, a sudden increase in blood pressure, after 20 weeks of pregnancy. Severe preeclampsia is associated with kidney damage, as well as liver damage and other serious problems.
The fetal kidney is formed in the first trimester of pregnancy, starting at about five weeks. Although the kidneys are formed in the first trimester, they continue to mature throughout pregnancy and are sensitive to several medications that could interfere with their function, often permanently. Many pregnant women are not aware that there are even medications that are available over the counter which could pose a significant risk to the kidney of their developing fetus. For example many pregnant women are told by their doctors to avoid over-the-counter, non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen, naproxen and aspirin, particularly late in pregnancy. However, they don’t know why they need to avoid them. This is a problem, because if the pregnant woman does not understand why she needs to avoid them, she may forget the warning among the many other health messages about food, etc., she is getting from her health care provider, as well as the internet, and brochures. Additionally, women that are not very familiar with pain relievers or medications in general, may confuse acetaminophen (Tylenol), which is recommended for pregnancy, with one of the other drugs. Survey studies suggest that many pregnant women have not heard or understood which pain relievers or fever reducers are recommended for them.
There are multiple reasons why NSAIDS, which are otherwise safe and effective pain relievers, are not recommended during pregnancy. These drugs have an anti-inflammatory effect by decreasing prostaglandin synthesis. Prostaglandins are found in smooth muscle including the uterus, and all over the body and are increased following inflammation. Prostaglandins are also important in maintaining the ductus arteriosus, which is a blood vessel that allows blood to go around the baby’s lungs before birth. Prior to birth, the fetus does not need to receive oxygen from the lungs because oxygenated blood is provided by the placenta. However, immediately after birth, the lungs of the newborn baby are filled with air, and the ductus arteriosus closes. When prostaglandin-reducing drugs such as NSAIDS are taken by the mother and are, therefore, introduced into the fetal circulation, the ductus arteriosis sometimes closes prematurely, causing a crisis for the unborn and the newborn baby. That is associated with damage to the newborn kidney. NSAIDs are also associated with a risk for fetal intracranial hemorrhage, and gastrointestinal problems (necrotizing entercolitis) above what is normally already seen in premature infants.
The take away message for pregnant women or women of reproductive age is to take care of your kidneys, avoiding lifestyle factors that could put them at risk such as obesity; take medications as prescribed by the physician if you have diabetes or hypertension and, finally, plan every pregnancy, whether there is an underlying illness or not.
About the Author
Sonia Alvarado is a bilingual (Spanish/English) Teratogen Information Specialist with the California Teratogen Information Service (CTIS) Pregnancy Health Information Line, a statewide service that aims to educate women about exposures during pregnancy and breastfeeding. Along with answering women’s and health professionals’ questions regarding exposures during pregnancy/lactation via CTIS’ toll-free hotline and email service, she’s provided educational talks regarding pregnancy health in community clinics and high schools over the past decade. In addition, Sonia contributes to the service’s website, develops training materials for new CTIS staff, and is the supervising Teratogen Information Specialist trainer. Sonia attended San Diego State University and has worked in Tuberculosis Control for San Diego County’s Public Health Department. Sonia’s work has also been published through several tuberculosis studies. In her spare time, she loves to volunteer with the March of Dimes as an expert speaker on themes related to pregnancy.
CTIS Pregnancy Health Information Line is part of the The Organization of Teratology Information Specialists (OTIS), a non-profit with affiliates across North America. California women with questions or concerns about pregnancy exposures can be directed to (800) 532-3749 or by visiting CTISPregnancy.org. Outside of California, please call OTIS counselors at (866) 626-OTIS (6847).