Preeclampsia -- out-of-control hypertension in pregnancy -- is the number-one cause of maternal death around the world. But another disease is taking a toll on mothers and babies, especially in the United States -- obesity.
"The number-one health condition that affects pregnancy is obesity," said Dr. Katharine Wenstrom, professor of obstetrics and gynecology at Women and Infants Hospital at Brown University in Rhode Island. "It changes everything with an increased risk for all pregnancy complications."
More than half of all women in the U.S. are overweight or obese when they become pregnant, and most go on to gain more than the recommended amount during pregnancy, according to Kaiser Permanente.
Doctors now know that fat cells are not inert and can produce inflammation. For pregnant women, that inflammation affects the placenta, according to Wenstrom. Obese women have smaller babies, more pre-term labor, airway problems and chances of serious complications during a C-section.
"The chance of death is higher and it's a real risk," she said.
"Most women do just fine," said Dr. Maurice Druzin, chief of obstetrics and gynecology at Lucile Packard Children's Hospital at Stanford University.
But social changes such as women delaying childbirth are making pregnancy more complicated. Advanced reproductive technologies have allowed women "who are not supposed to get pregnant" to have children, said Druzin.
"If you left it to nature, they would not get pregnant at this age," he said. "There are big ramifications of infertility with more multiples. ... Women who are older tend to have more chronic medical illnesses like hypertension and diabetes and are at more risk of getting gestational diabetes and preeclampsia."
A 2010 report from Amnesty International, "Deadly Delivery: The Maternal Health Crisis in the USA," said "near misses" are increasing by 25 percent since 1998.
Of the 1.7 million American women who get pregnant, one third have medical complications, most of them among minority populations, according to the report.
Wenstrom said the report paints a somewhat distorted picture of prenatal health care in the United States, but several common conditions can make pregnancy more perilous.
Obesity is defined as a higher-than-average and unhealthy body mass index (BMI). Adults with a BMI between 25 and 30 are considered overweight. A person with a BMI greater than 30 is obese, and anyone more than 100 pounds overweight and has a BMI of 40 or greater is morbidly obese, according to the National Institutes of Health.
"Obesity rates are spectacularly rising," said Druzin. "And it's not only the rate that's rising, but the type of obesity -- morbid obesity. What we are seeing today is astonishing -- huge people."
Those who are obese are more predisposed to hypertension and diabetes, have more dysfunctional labors and, if they need surgery (a Caesarian), are more at risk because their airways can be compromised as tissues swell more readily.
"You cannot get the same quality of image in a sonogram," said Druzin. "It's challenging, and there is pretty good data showing that no matter how good the machine or skill of the doctor is, you may not get adequate imaging. The chance of missing something is there."
Obesity also can affect ovulation, and many women who would do better by losing weight instead turn to in vitro fertilization to get pregnant, Wenstrom said. Some go on to have twins, putting themselves at even greater risk.
Obstetrical teams are now paying more attention to obese women. Before having a C-section, patients are given the blood-thinner heparin to prevent blood clots, special devices are used to keep their airways open, and special protocols and surgical equipment is in place.
"We are working to develop special protocols and have more pre-delivery requirements," she said. "It's a huge problem for us and stressful for patients."
Hypertension, or high blood pressure, can be managed well, but becomes a problem if in pregnancy if it advances to preeclampsia.
Preeclampsia, with high blood pressure and protein in the urine, develops late in the second or third trimester. Possible causes include autoimmune disorders, blood vessel problems, diet or heredity. Women who are over 35, pregnant with twins or who are obese are at greater risk.
It can be particularly dangerous because a woman usually doesn't feel sick, and if the condition worsens and goes untreated, it can cause death. The only way to cure preeclampsia is to deliver the baby.
"If you have hypertension and get pregnant, the chances of preeclampsia are much higher," said Druzin. "Management is still problematic, but the biggest problem is appropriate detection and diagnosis. Once it's diagnosed, management is pretty good and we know how to deal with the severe side effects."
Though there is a higher incidence of diabetes in mothers, it is almost never life-threatening and management of the disease is excellent. Gestational diabetes is high blood sugar that starts or is first diagnosed during pregnancy. In pregnancy, hormones can block insulin from doing its job. When this happens, glucose levels may increase in a pregnant woman's blood.
After birth, the condition resolves. Older women with high blood pressure and those who have a history of diabetes are at greater risk.
"Old-style pre-gestational diabetes that develops in childhood is still there and we are pretty good at getting that under control before women get pregnant," said Druzin. "What is emerging now is a wrinkle in the picture with these obese young people who develop type 2 diabetes is on the absolute climb. But there are those patients who are not very healthy and come into us already pregnant with diabetes."
Doctors treat diabetes with blood sugar control in the diet, insulin and oral medication.
A less-common form of cardiac disease seems to be on the rise among pregnant women, and doctors don't seem to know why.
"It's not the classic coronary artery disease, but more of an increase in cardiomyopathy -- not the congenital, but more of the acquired type," said Druzin.
Peripartum cardiomyopathy strikes as many as 3,000 new mothers in the U.S. each year and is characterized by fatigue and shortness of breath -- symptoms that resemble those common to new mothers and, therefore, often are missed. It may be related to obesity, hypertension and diabetes, according to Druzin.
The health of a baby is directly connected to maternal health.
Hypertensive disorder, chronic hypertension and preeclampsia can result in placental insufficiency, which in turn can lead to smaller babies and decreased fetal growth. If the placenta cannot keep up with the growth needs, the fetus is smaller and has a higher incidence of cardiovascular problems.
In diabetes, out-of-control glucose can lead to other fetal anomalies. High maternal blood sugar later in pregnancy can cause the fetus to grow too big. Glucose can be toxic to the fetus, and if blood sugar is high in the first trimester the fetus is at higher risk for cardiac or neural defects or skeletal problems.
Though older women are at increased risk for hypertension and diabetes in pregnancy, most who are healthy will have no problems.
Much of the data on older women depends on socio-economics, and poorer women have poorer outcomes, according to Wenstrom.
Pregnancy can, however, serve as a "stress test" for what a woman might develop later on in life. Those who have preeclampsia tend to develop heart disease and hypertension. Those with gestational diabetes may get "full-on" diabetes, she said.
"If a woman is in good physical shape and doesn't smoke, age is not a factor," said Wenstrom. "A lot of the older literature suggests they were at increased risk -- in the days when they were 40 and smoking. Those were older women like Bette Davis. But that was then. Now they are like Madonna and it's a different era. They take care of themselves."