Diabetes, Pregnancy and Your Health
How diabetes affects the health of mother and child—and what you can do about it
Olivia Bitter started planning her pregnancy just after her wedding. It took her longer than the pregnancy itself. “I spent a year planning to understand what I needed to do,” says Bitter, who has type 1 diabetes. The process involved talking with her endocrinologist, searching for an obstetrician who specialized in high-risk pregnancies, and optimizing the way she checked and controlled her blood glucose levels.
Bitter’s elaborate preparation was just what the doctor ordered. High blood glucose levels at the moment of conception or in the early weeks of pregnancy can lead to birth defects and miscarriages. Women with diabetes are also at higher risk for preeclampsia, a potentially deadly condition that raises blood pressure and causes swelling and sudden weight gain.
That means unplanned pregnancies are especially risky for women with diabetes, so it’s important to get A1C levels under control before even trying to conceive. Pregnancy can also worsen other preexisting complications of diabetes, such as eye and kidney problems. “For women with preexisting diabetes, it’s ideal if I can meet them before they get pregnant,” says Kristin Castorino, DO, a research physician at the Sansum Diabetes Center in Santa Barbara, California.
But most pregnant women don’t see their obstetrician until the eighth or ninth week of pregnancy—after some of the most critical fetal development has occurred.
“We know all these risks can be diminished if Mom’s in tight metabolic control from conception onward,” says Denise Charron-Prochownik, PhD, RN, CPNP, FAAN, a professor at the University of Pittsburgh’s School of Nursing and Graduate School of Public Health. The American Diabetes Association’s latest guidelines suggest an A1C of between 6 and 6.5 percent, or even lower if it’s possible to do so without hypoglycemia.
That guidance was at the top of Bitter’s mind at the start of and during her pregnancy. “Once I got pregnant, my blood sugar became my full-time job and my No. 1 concern,” says Bitter, an Ohio nurse. After she conceived, she worked hard to bring down an A1C of 8.5 to recommended levels.
Bitter’s daughter, Zoey, was born healthy and happy two years ago—and now Bitter’s pregnant again. “I think women with diabetes can enjoy pregnancy too, even though it’s going to come with a lot more challenges,” Bitter says. “It’s definitely worth it.”
In 1990, Wendy Williams, a music teacher in Batavia, New York, was 23 and already in her second trimester when her doctor told her she had gestational diabetes. High blood glucose early in the pregnancy seemed to have an effect: Her son was born unusually large after a difficult labor.
High insulin levels during pregnancy are believed to be the cause of macrosomia, a big word for “too big.”
Also, the developing fetus treats extra glucose as extra nutrients. All those extra nutrients become particularly relevant in the second and third trimesters, which are mostly about the fetus packing on pounds. “After the first trimester, you’re growing [the] baby,” Castorino says. “If you grow it in an environment of too much stuff, the baby will use all those nutrients.”
Babies with macrosomia are often over 10 pounds at birth, which can be dangerous for moms. Big babies are more likely to need cesarean sections, cause more vaginal tears, and put moms at greater risk for dangerous bleeding from the uterus.
Macrosomia is a threat to newborns, too. There’s an increased risk of shoulder dislocations during delivery, as well as more stillbirths. The typical solution, a C-section, has been shown to increase the chances a child will later develop type 1 diabetes, perhaps because vaginal birth transfers important and beneficial bacteria to newborns.
There’s also increasing evidence that macrosomia poses long-term risks for babies. Research has shown that macrosomia is linked to higher rates of obesity and type 2 diabetes later in life.
Like other complications, macrosomia can be avoided by controlling your blood glucose during pregnancy. Williams went on to have three more kids (all born at normal weights). Her youngest was born after she was diagnosed with late-onset type 1 at age 40. Maintaining a low A1C during pregnancy became an obsession. “I monitored like crazy,” she says. “It’s possible to have children with no health problems and keep healthy yourself.”
Gestational diabetes affects up to 10 percent of pregnancies. Though it usually disappears after birth, gestational diabetes upsets the body’s responsiveness to insulin for the duration of pregnancy in a way that resembles lifelong conditions such as type 2.
Gestational diabetes can strike anyone, but some people are at higher risk. Obesity, family history of type 2, and previous gestational diabetes pregnancies all increase the likelihood of gestational diabetes. Certain ethnicities—Asians and Latinos in particular—are at higher risk. And women who are older when they get pregnant are more likely to have gestational diabetes.
Though scientists have identified risk factors, it’s still not clear what causes gestational diabetes. What they do know is that it mimics the progression of type 2 in the space of a few months: Hormonal changes during pregnancy can signal the body to store fat and raise blood glucose levels. At the same time, insulin resistance increases, forcing the pancreas to produce more insulin and putting the organ under extra stress. And some researchers think that certain hormones made by the placenta, the organ that nourishes the baby, make the body less sensitive to insulin.
Though features of gestational diabetes, such as elevated blood glucose, insulin resistance, and increased insulin output, go away after birth, babies exposed to gestational diabetes in the womb are more likely to have type 2 diabetes and/or obesity later in life.
University of Southern California researcher Kathleen Page, MD, is trying to find out why. With the help of a grant from the American Diabetes Association, she’s working with 150 children between the ages of 7 and 10. Half of the kids were exposed to gestational diabetes while in the womb, and half weren’t. Page is hoping to find out whether children exposed to gestational diabetes have insulin resistance or decreased insulin secretion.
An abnormal response to insulin could have something to do with the changes in a baby’s brain—changes caused by high blood glucose levels during pregnancy. Research in mice suggests that diabetes during pregnancy may affect the infant’s hypothalamus, the area of the brain that controls appetite and the body’s response to glucose. “The hypothalamus regulates how hungry we are, and there’s emerging evidence it’s helping regulate insulin secretion too,” says Page. “The brain is a lot more involved in the regulation of insulin than we thought.”
Page and her team first put the kids in a functional magnetic resonance imaging machine, or fMRI, which measures the level of blood flow to different parts of the brain. Then they’re given a sugary drink, and their brain activity is measured again. “We can see how the brain is activated before and after,” Page says. “With the brain scans, we might be able to see if the brain isn’t functioning normally.”
Although Page is working with kids whose mothers had gestational diabetes, she thinks the brains of kids whose mothers had high blood glucose during pregnancy as a result of type 1 or type 2 diabetes could be similarly altered. “I would think higher blood glucose levels would have a larger impact on abnormalities we see later,” she says. “It’s possible that type 1 or preexisting type 2 would have similar effects.”
Her hypothesis echoes the advice that the ADA gives mothers with any type of diabetes: Focus on controlling blood glucose levels during pregnancy. “I hope to learn how management of diabetes during pregnancy might [reduce] risk later in life,” Page says.
Breast-feeding is widely recommended for all mothers, but for women with diabetes, it can be especially helpful. “Particularly for women using insulin in the postpartum period, breast-feeding is like exercise,” says Castorino. “Each time the body makes milk, a mom’s glucose levels will drop.”
As with exercise, it’s important to monitor your blood glucose during and after breast-feeding. “Think of breast-feeding as going on a short walk,” Castorino says. “Women can even have lows afterward.”
The ADA is behind a push to understand another aspect of breast-feeding, namely its long-term benefits for women who had gestational diabetes during pregnancy. The metabolic effects of gestational diabetes can be long-lasting: At least half of all women who experience gestational diabetes go on to get type 2.
Maria Ramos-Roman, MD, an endocrinologist at the University of Texas Southwestern Medical Center, thinks breast-feeding might be something moms can do to reduce their own risk of developing type 2 diabetes later. Observational studies have found that breast-feeding for longer after birth is associated with a lower risk of type 2 diabetes in mothers who didn’t have diabetes during pregnancy and also in mothers with a history of gestational diabetes. More-intense breast-feeding (in which the baby’s nutrition comes more from breast milk than formula) is also associated with a lower risk of type 2 diabetes in mothers with a history of gestational diabetes.
In one of those studies, researchers monitored mothers with a history of gestational diabetes for two years after their babies were born to see how many of them developed type 2 diabetes. They carefully tracked the number of months they breast-fed and how intense breast-feeding was. The results were convincing: “The more months the mother breast-feeds and the more milk fed to the baby comes from the breasts, then the lower the risk of type 2 diabetes two years after the baby was born,” says Ramos-Roman.
With the help of a grant from the American Diabetes Association, Ramos-Roman is trying to figure out how breast-feeding reduces maternal diabetes risk. It’s a complicated question because breast-feeding itself is such a complex process. “It’s not just the mammary glands or breasts—there are at least eight systems involved in making breast milk possible.”
Breast-feeding involves turning glucose and fat in the body into milk. Ramos-Roman thinks that hormones that stimulate breast milk production alter the function of body fat for the better. She thinks the duration and intensity of breast-feeding have the potential to make fat work in a healthier way by altering the way hormones called adiponectin and prolactin work in the body. “If by breast-feeding they can continue being without diabetes between pregnancies, that means better outcomes for mother and baby,” Ramos-Roman says.
From beginning to end, pregnancy is a time of constant change. All the planning in the world can’t predict how an individual woman will react to the storm of hormones released in the process of making a new person. “Insulin requirements change throughout pregnancy,” Castorino says. “It’s like chasing a moving target.”
Take morning sickness, the nausea and vomiting that can dominate the first trimester of pregnancy. For most women, it’s just very unpleasant; for women with any type of diabetes, it can make sticking to a balanced diet difficult and mess with blood glucose levels.
And around the eighth week of pregnancy, there’s a shift in how the growing fetus is nourished: The placenta takes over and prompts a change in the way the body secretes insulin. That often causes blood glucose levels to drop, putting women at risk for low blood glucose.
As pregnancy progresses, the process is reversed. Insulin resistance spikes as estrogen and progesterone flood the body. “The hormones of pregnancy are almost like developing type 2 on top of type 1,” Castorino says.
Regardless of diabetes type, pregnant women in their third trimester often experience insulin resistance so high that the body’s typical blood glucose response to carbs doubles. “By the end of pregnancy, it’s almost like you can think about carbs and your blood sugar will rise,” Castorino says.
In the last weeks of her first pregnancy, Bitter was using four or five times her usual insulin dosage. “I had to inject on top of what I was getting from my pump because the pump couldn’t keep up,” she says.
These shifts aren’t easy to deal with. “We’re asking a lot of women. If they want to minimize their risks, they have to be extra vigilant,” says Charron-Prochownik. “But it’s important to remember you can have a healthy pregnancy—you just have to work hard.”