Wednesday, June 29, 2011

Vitamin D supplements safe for healthy pregnant women

Use of vitamin D supplements during pregnancy has long been a matter of concern but now researchers writing in the Journal of Bone and Mineral Research report that even a high supplementation amount in healthy pregnant women was safe and effective in raising circulating vitamin D to a level thought by some to be optimal. The study also found no adverse effects of vitamin D supplementation, even at the highest amount, in women or their newborns.

The research team, led by Dr. Bruce Hollis from the Medical University of South Carolina in Charleston, used a randomized controlled trial with healthy expectant mothers to discover how varying dosages of daily supplements could safely sustain a circulating vitamin D level of at least 32 nanograms per milliliter.

"Vitamin D supplementation during pregnancy remains controversial largely due to severe misconceptions about the potential harm it may cause to the fetus," said Dr Hollis. "Surprisingly the scientific debate has made little progress since Dr. Gilbert Forbes made a recommendation of 200 IU (international units) per day in 1963, which was based on a hunch."

While the threat of vitamin D during pregnancy has remained little known, it has been established that the vitamin plays a role in homeostasis, the body's internal regulation, during pregnancy and that a deficiency can effect immune, pancreatic and cardiovascular systems.

Dr Hollis' team monitored the pregnancies of 350 women, from a variety of ethnic and socio-economic backgrounds, who were all between 12 and 16 weeks into gestation. The women were randomly assigned to one of three groups. One group received 400 IU of vitamin D per day, the second group received 2,000 IU per day and the third received 4,000 IU daily.

The team found that women who received the highest level of supplementation (4,000 IU per day) were more likely to achieve and sustain the desired level of circulating levels of vitamin D throughout their pregnancy. Moreover, the researchers found that pregnant women who received lower levels of vitamin D supplementation did not attain the threshold circulating level of the vitamin.

"In our study subjects, a daily dosage of up to 4,000 IU of vitamin D was required to sustain normal metabolism in pregnant women," concluded Dr Hollis. "Furthermore, following decades of speculation into its safety our research has demonstrated vitamin D supplementation to be both safe and effective."

Wednesday, June 22, 2011

Smoking During Pregnancy Lowers Levels of 'Good' HDL Cholesterol in Children

Researchers in Australia have discovered that mothers who smoke during pregnancy are causing developmental changes to their unborn babies that lead to them having lower levels of the type of cholesterol that is known to protect against heart disease in later life -- high-density lipoprotein (HDL) cholesterol.

The research, published online in the European Heart Journal, showed that, by the age of eight years, children born to mothers who smoked while they were pregnant had HDL cholesterol levels of about 1.3 millimoles per litre (mmol/L), compared to the more normal level of 1.5 mmol/L in children born to mothers who had not smoked. After adjustments for various factors that might affect the result, the difference attributable to mothers' smoking was about 0.15 mmol/L. The researchers found that this effect was independent of whether the children had been exposed to other people's smoke after birth, suggesting that prenatal exposure had the most impact on the children's subsequent development.

David Celermajer, Scandrett Professor of Cardiology at the University of Sydney, Australia, who led the study, said: "Our results suggest that maternal smoking 'imprints' an unhealthy set of characteristics on children while they are developing in the womb, which may well predispose them to later heart attack and stroke. This imprinting seems to last for at least eight years and probably a lot longer."

Although cigarette smoking during and after pregnancy is known to be linked to a range of childhood health problems, including behavioural and neurocognitive problems and sudden infant death, until now it has been unclear what effect prenatal exposure to cigarette smoke had on the risk of future cardiovascular disease.

Prof Celermajer and his colleagues decided to examine the effects of maternal smoking during pregnancy on the thickness of the arterial wall and the levels of lipoproteins in a group of 405 healthy eight-year-olds, born between 1997 and 1999, who had been enrolled before birth into a randomised controlled trial that was investigating asthma and allergic diseases. The researchers collected data before the children were born and as they grew up, including information on mothers' smoking habits before and after pregnancy, the children's exposure to passive smoking, and measurements of height, weight, waist circumference and blood pressure. They used ultrasound scans to measure the arterial wall thickness and, in 328 children who agreed, they took blood in order to measure lipoprotein levels.

Although there was no effect on the thickness of the children's arterial wall, Prof Celermajer found that there was an effect on levels of HDL cholesterol, which remained statistically significant after adjusting for a range of factors that might have been different in children born to mothers who smoked, such as post-natal smoke exposure, duration of breast feeding, physical inactivity and body mass index.

The researchers believe that the lower levels of HDL cholesterol at this age suggest there could be a serious impact on health in later life, as the children will probably continue to have low levels in adulthood. "Cholesterol levels tend to track from childhood to adulthood, and studies have shown that for every 0.025mmol/L increase in HDL levels, there is an approximately 2-3% reduction in the risk of coronary heart disease. If we extrapolate this, we can suggest that the difference of 0.15mmol/L between children of smoking mothers versus non-smoking mothers might result in a 10-15% higher risk for coronary disease in the children of smoking mothers. This is an approximation only, but the best one we have," said Prof Celermajer.

The researchers point out that the prevalence of smoking during pregnancy is still high, at around 15% in many Western countries. Therefore, their findings may be important for informing population-based strategies for preventing heart disease in later life, especially as HDL cholesterol plays an important role in protecting against atherosclerosis -- a condition in which fatty materials collect along the walls of arteries, thickening and eventually blocking them, leading to problems such as angina and heart attacks.

"Children born to mothers who have smoked during pregnancy will need to be watched particularly carefully for other coronary risk factors, like high blood pressure, high LDL, 'bad' cholesterol levels, and especially cigarette smoking themselves," said Prof Celermajer.

"The only ways to increase HDL levels are regular exercise and with the use of certain medications such as Niacin. We will have to do long-term follow-up to see if these particular children continue to have lower HDL cholesterol levels than normal, but one should presume that this risk factor might indeed be persistent."

The mechanism whereby maternal smoking during pregnancy lowers HDL cholesterol in children is unknown. "One of the advantages of studying this in eight-year-old children is that the usual factors that drive down HDL cholesterol, such as obesity and diabetes, are absent, and so we can infer a more or less direct effect of smoking on HDL levels, rather than one mediated through changes in body composition or vulnerability to diabetes," concluded Prof Celermajer.

Monday, June 13, 2011

Sleep apnea increases risk of pregnancy

Pregnant women with severe sleep apnea may have an increased risk of gestational diabetes and early preterm birth

Sleep apnea is associated with an increased risk of adverse pregnancy outcomes, suggests a research abstract that will be presented Monday, June 13, in Minneapolis, Minn., at SLEEP 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results show that women with severe sleep apnea had the highest incidence of adverse pregnancy outcomes. This increased prevalence was principally driven by a higher incidence of gestational diabetes and early preterm birth.

The authors noted that sleep apnea has been associated with heart disease, metabolic syndrome and mortality in non-pregnant populations. However, few studies have examined the relationship between sleep apnea in pregnancy and adverse obstetrical outcomes.

"Our findings suggest that moderate to severe sleep-disordered breathing may be associated with adverse pregnancy outcomes, particularly gestational diabetes and preterm birth," said principal investigator Dr. Francesca L. Facco, assistant professor in the department of obstetrics and gynecology at Northwestern University in Chicago. "However, it is unclear if sleep-disordered breathing is a risk factor for adverse pregnancy outcomes independent of obesity."

According to the American Academy of Sleep Medicine, sleep apnea is a form of sleep-disordered breathing that involves partial reductions (hypopneas) and complete pauses (apneas) in breathing during sleep. The most common form of sleep apnea is obstructive sleep apnea, which occurs when the muscles relax during sleep, causing soft tissue in the back of the throat to collapse and block the upper airway. The breathing pauses that result can produce abrupt reductions in blood oxygen saturation and reduce blood flow to the brain. Most people with OSA snore loudly and frequently, and they often experience excessive daytime sleepiness.

Facco and colleagues searched a medical records database and identified 150 women who had received a sleep evaluation by overnight polysomnography and had given birth between January 2000 and June 2009. About 87 percent of the women were overweight or obese at delivery with a body mass index of 25 or more. Seventy-two percent of the women had undergone the sleep study within three years of their delivery. For women with more than one pregnancy during the study period, the first pregnancy with outcome information was selected for analysis.

Women with an apnea-hypopnea index of five to 14.9 breathing pauses per hour of sleep were considered to have mild to moderate sleep apnea, and those with an AHI of 15 or more were classified as having severe sleep apnea. The analysis assessed the associations between sleep apnea and three adverse pregnancy outcomes: pregnancy induced hypertension, gestational diabetes, and early preterm birth at 34 weeks or less.

Facco added that more research is needed to clarify how sleep apnea and obesity interact with maternal and neonatal health.

"Further studies, principally large prospective studies utilizing objective measures of sleep-disordered breathing, are needed to confirm this relationship, and to examine the interaction between sleep-disordered breathing and body mass index," said Facco. "If a relationship is confirmed, further studies would be needed to ascertain the role of treatment of sleep-disordered breathing in pregnancy."

The treatment of choice for obstructive sleep apnea is CPAP therapy, which provides a steady stream of air through a mask that is worn during sleep. This airflow keeps the airway open to prevent pauses in breathing and restore normal oxygen levels. Help for people with sleep apnea is available at more than 2,200 AASM-accredited sleep disorders centers across the U.S.

The SLEEP 2011 abstract supplement is available for download on the website of the journal Sleep at

Tuesday, June 7, 2011

Pregnant women can prevent excess weight gain with simple steps

A new study reports that a low-cost healthy lifestyle program, including self-weighing weekly or monthly, by pregnant women with pre-existing overweight can prevent them from gaining too much weight during early pregnancy. The researchers will present the results Sunday at The Endocrine Society's 93rd Annual Meeting in Boston.

"Preventing excess weight gain in pregnancy is essential to the health of all mothers and their babies and can be achieved by increasing awareness [of weight during pregnancy] and by simple health messages, behavior change strategies, and regular monitoring of weight gain," said lead author Catherine Lombard, PhD, of the Monash University School of Public Health and Preventive Medicine, Melbourne, Australia.

"This weight-management strategy has the potential to reduce pregnancy complications, such as gestational diabetes, and birth complications," Lombard said.

The clinical trial consisted of more than 200 overweight women, recruited from a hospital-based clinic, who were less than 15 weeks pregnant. All women were at high risk of developing gestational diabetes (pregnancy-related diabetes) because of their age, weight, ethnicity, previous gestational diabetes or a family history of diabetes. They were randomly assigned to the intervention group (106 women) or control group (99 women).

At 14 weeks of pregnancy, both groups received health information emphasizing making small, healthy changes to eating and physical activity, such as walking and eating more fruit and vegetables. The intervention group also received information about how much weight they should gain during pregnancy, an instruction to weigh themselves weekly or monthly and frequent reminders by text messaging. The control group received no instruction or reminders to self-weigh. Both groups received standard prenatal care.

Measures included weight, frequency of self-weighing, physical activity and food intake at the beginning of the study and at 28 weeks of pregnancy. This is the time that routine testing for gestational diabetes occurs, according to Lombard.

At 28 weeks regular self-weighing was associated with significantly less pregnancy weight gain for intervention participants than for the control participants—12.6 pounds versus 15.7 pounds, respectively. Women in both groups who did not self-weigh gained a similar amount of weight: an average of 15.2 pounds.

"We conclude," Lombard said, "that self-weighing keeps women focused on their behavior. When it is paired with a simple self-management intervention to prevent excess weight gain, it has a significant impact on weight gain in high-risk pregnancies."

Excessive pregnancy weight gain raises the risk of having a fat baby

Women who gain too much weight during pregnancy tend to have newborns with a high amount of body fat, regardless of the mother's weight before pregnancy, a new study finds. The results will be presented Tuesday at The Endocrine Society's 93rd Annual Meeting in Boston.

High fat at birth is a possible risk factor for childhood obesity, said the study's principal investigator, Jami Josefson, MD, a pediatric endocrinologist at Chicago's Children's Memorial Hospital and assistant professor at Northwestern University Feinberg School of Medicine.

"Previous studies have shown that children of mothers who gain too much weight during pregnancy are more likely to be overweight for their age," Josefson said. "However, not all these studies accounted for the mother's diabetes status during pregnancy, which is a known risk factor for offspring obesity."

The new study evaluated only pregnant women without gestational diabetes, therefore ruling out the chance that this disorder could account for their findings.

Josefson and her colleagues wanted to learn whether pregnant women who gain more than the recommended amount of weight have fat infants. Doctors, however, do not typically measure a newborn's body fat, she said. Many past studies that measured newborn body fat used an imprecise method, such as skin fold thickness, according to the authors' abstract.

This study used a new infant body composition system (Pea Pod) that employs an air-displacement technique, which Josefson said accurately and safely measures newborn body fat. This technique requires the infant to simply lie in a machine for two minutes, she said. Newborns in the study underwent measurements of length, weight and fat within 48 hours of birth.

Of the 56 mothers the researchers studied, 31 women were within guidelines for pregnancy weight gain, and 25 exceeded the guidelines. The Institute of Medicine recommends that women at a healthy weight before pregnancy gain 25 to 35 pounds while expecting a single baby; overweight women, 15 to 25 pounds; and obese women, 11 to 20 pounds.

Study subjects who were obese before pregnancy were more likely than healthy-weight women to exceed the weight-gain guidelines (70 percent versus 31 percent, respectively), the authors reported. Yet regardless of pre-pregnancy weight, women who put on more than the recommended weight gave birth to significantly fatter babies. Their newborns had 490 grams, or 17.5 ounces, of body fat, whereas newborns of women who stayed within the guidelines had 390 grams (13.9 ounces) of fat. This higher obesity risk existed even when birth weight was normal.

"Excessive weight gain during pregnancy, regardless of pre-pregnancy weight, is an important risk factor for newborn obesity," Josefson said. "More research is needed to determine if high amounts of fat at birth are associated with high amounts of fat in childhood."

Thursday, June 2, 2011

Maternal Smoking Causes Changes in Fetal DNA

Children whose mothers or grandmothers smoked during pregnancy are at increased risk of asthma in childhood, but the underlying causes of this are not well understood. Now a new study indicates changes in a process called DNA methylation that occurs before birth may be a root cause.

DNA methylation is a process that can alter a gene’s usual function. These altered genes can be passed along from parent to child. In this case, researchers observed DNA methylation-related changes in the AXL gene in children exposed to maternal smoking in utero. The AXL gene plays an important role in many human cancers and in immune response.

“We found that children exposed to maternal smoking in utero had a 2.3 percent increase in DNA methylation in AXL,” said Carrie Breton, ScD, assistant professor of preventive medicine at The Keck School of Medicine of the University of Southern California (USC) in Los Angeles.

“These results confirm results from a prior study and present compelling evidence that environmental exposure to tobacco smoke during pregnancy may alter DNA methylation levels."’

Using a detailed questionnaire, the researchers targeted the mothers and grandmothers of 173 children participating in the Early Asthma Risk Factors Study (EARS), a study within the larger California Children’s Health Study, and assessed their smoking habits during pregnancy. DNA samples collected from cheek cells of mothers and children were evaluated. Dr. Breton and her team found that DNA methylation of AXL was associated with in utero exposure to maternal smoking, and also found that grandmaternal smoking was not significantly associated with AXL methylation in either the mother or the child. The association between DNA methylation of AXL and in utero exposure to smoking was stronger in girls than in boys, she added.

Dr. Breton said the results of the study indicate the need for a greater understanding of the effects environmental factors have on epigenetic changes – that is, changes in gene function or expression that occur as the result of mechanisms other than changes to the underlying DNA sequence – and early development in general.

“Environmental exposures occurring in utero have the potential to affect DNA methylation patterns before birth,” she explained. “Imprinted genes appear to be particularly susceptible to these exposures since they come from one parent and only a single copy from one chromosome in DNA is active. Any environmentally-induced epigenetic changes will have greater impact on gene expression and function. In utero and early life exposures are likely to be important, given what we know about timing during development when epigenetic marks are established.”

Investigating the effects of environmental exposures on epigenetics is a largely unexplored area of research, and one that holds great promise for understanding biological mechanisms that underlie exposure-disease associations, she added.
“We are interested in further characterizing the pattern of epigenetic marks across this gene and whether there is a widespread response to both maternal smoking exposure and air pollution exposure in utero,” Dr. Breton said. “We hope to also evaluate timing of effects of exposure during trimester by increasing the number of samples we evaluated in a manner that will let us compare trimester-specific exposures.”

High-fat diet during pregnancy increases risk of stillbirth

Surprisingly, eating a fatty diet has negative consequences regardless of whether the mother is obese or slender

Eating a high-fat diet during pregnancy increases the chance of stillbirth, according to new research at Oregon Health & Science University. The new data show eating a typical American diet, which is high in fat, decreases blood flow from the mother to the placenta, the temporary organ that nourishes the unborn fetus. Prior to this study, exactly how a fatty diet contributes to stillbirth was unclear. The findings are published in the June edition of the journal Endocrinology.

The study was conducted at the OHSU Oregon National Primate Research Center. Because the placental structure of the Japanese macaque is very similar to that in humans, cause and effect can be better established. The researchers hope their work will inform expectant moms and their physicians about the inherent dangers of a high-calorie, high-fat diet.

"This study demonstrates that maternal diet during pregnancy has a profound influence on both placental and fetal development. The high-calorie, high-fat diet common in our society has negative effects on placental function and may be a significant contributor to adverse pregnancy outcomes, such as stillbirth," said Antonio Frias, M.D., principal investigator and assistant professor of obstetrics and gynecology (perinatology/maternal-fetal medicine) in the OHSU School of Medicine.

Previous studies have shown that nearly all adverse outcomes during pregnancy -- abnormal fetal growth, preeclampsia, preterm labor and stillbirth -- are in some way associated with an abnormally developed, or damaged, placenta, the temporary organ that nourishes the unborn fetus. In addition, maternal obesity has been associated with placental inflammation and dysfunction and an increased risk of stillbirth. Considering these findings, the researchers hypothesized that eating a diet high in fat during pregnancy also may increase the risk of placental inflammation and the risk of stillbirth.

Frias and colleagues observed 24 pregnant Japanese macaques that ate either a diet comprising 32 percent calories from fat or a control diet with 14 percent fat calories for at least four years.

The researchers found the monkeys that ate a high-fat diet experienced a significant decrease in blood flow from the uterus to the placenta, a reduction of 38 percent to 56 percent, and a rise in placental inflammation. This was the case regardless of whether the monkeys were obese or slender. The risk of stillbirth was further compounded, however, when the monkeys were obese with hyper-insulinemia, or pre-diabetes.

Additional studies are needed to determine exactly how a high-fat diet decreases placental blood flow, the researchers report.

Future studies also will investigate the impact of dietary changes and diet supplementation on improving outcomes in both monkeys and humans.