Monday, December 23, 2013
Peanut and tree nut allergy incidence lower among children whose mothers ate them during pregnancy
Women need not fear that eating peanuts during pregnancy could cause their child to develop a peanut allergy, according to a new study from Boston Children's Hospital published online Dec. 23 in JAMA Pediatrics.
"Our study showed increased peanut consumption by pregnant mothers who weren't nut allergic was associated with lower risk of peanut allergy in their offspring," says the study's senior author Michael Young, MD, of Boston Children's Division of Allergy and Immunology. "Assuming she isn't allergic to peanuts, there's no reason for a woman to avoid peanuts during pregnancy."
Previously, women had been advised to avoid highly allergenic foods such as peanuts and tree nuts during pregnancy and while nursing, and that their children should avoid peanuts until 3 years of age. The goal of these recommendations, despite a lack of supporting research, was to minimize early allergen exposure and sensitization, thereby reducing the risk of developing childhood peanut allergy. The American Academy of Pediatrics (AAP) endorsed these recommendations in 2000. However, from 1997 to 2007, the number of peanut allergy cases in the U.S. tripled, leading the medical community to reexamine its recommendations. Based on the lack of evidence supporting early dietary avoidance, the AAP rescinded the recommendation in 2008.
"No one can say for sure if the avoidance recommendation for peanuts was related to the rising number of peanut allergies seen in the late 1990s and early 2000s, but one thing is certain: it did not stop the increase," Young says. "It was clear that a new approach was needed, opening the door for new research."
To further define the relationship between maternal diet and the development of food allergy in offspring, Young and his team analyzed large amounts of data provided by the Growing Up Today Study (GUTS). Examining the records of 8,205 children, the researchers positively identified 140 cases of peanut or tree nut allergies. They then examined the diets of each child's mother—specifically, peanut and nut consumption—during the peri-pregnancy period and compared them with the dietary habits of pregnant women whose children did not develop a peanut allergy.
Young and team found that the rate of peanut allergy was significantly lower among children in the study whose mothers ate peanuts during the peri-pregnancy period. Although this is a substantial finding, the data demonstrate only an association between maternal diet and the risk of peanut allergy in children.
"The data are not strong enough to prove a cause-and-effect relationship. Therefore, we can't say with certainty that eating more peanuts during pregnancy will prevent peanut allergy in children. But we can say that peanut consumption during pregnancy doesn't cause peanut allergy in children," Young says. "By linking maternal peanut consumption to reduced allergy risk we are providing new data to support the hypothesis that early allergen exposure increases tolerance and reduces risk of childhood food allergy."
Thursday, December 19, 2013
One-quarter of US women gain an inadequate amount of weight during pregnancy, University of Maryland School of Public Health study shows
Women who do not gain enough weight during pregnancy are at increased risk of losing their baby in its first year of life, according to a new study by researchers in the University of Maryland School of Public Health (UMD SPH). This study examined the relationship between gestational weight gain, mothers' body mass index (BMI) before and during pregnancy, and infant mortality rates. One-quarter of the more than 159,000 women in the study gained too little weight during pregnancy, and these mothers were more likely to give birth to babies who died in infancy than the women who gained a normal or even excessive amount of weight during pregnancy. The study is published in the American Journal of Public Health. It was conducted by Dr. Regina Davis, associate executive director of the American Public Health Association, Dr. Sandra Hofferth, professor, and Dr. Edmond Shenassa, associate professor. All three are affiliated with the UMD SPH Maternal and Child Health Program, Department of Family Science, and Hofferth and Shenassa are faculty associates of the Maryland Population Research Center.
"Our study showed that gaining too little weight during pregnancy is a risk factor for infant mortality for all but the heaviest women," explained Dr. Davis. Gaining more weight than recommended was not a risk factor for infant mortality but may be related to subsequent maternal health problems. "It is important that childbearing women have pregnancy weight gain goals that are specific to their individual BMI," added Dr. Hofferth, the study's senior author.
According to guidelines published by the Institute of Medicine (IOM), underweight women should gain between 28 and 40 pounds during pregnancy, while normal weight women are expected to gain 25-35 pounds, overweight women 15-25 pounds, and obese women 11-20 pounds. Results from this study showed that only about a third of women gained an amount of weight that was within the recommended guidelines for their body size. Nearly 25% of the women in the study gained an inadequate amount of weight, while another 41% gained too much.
Davis, Hofferth, and Shenassa analyzed data collected from 159,244 mothers who gave birth to live, single babies between 2004 and 2008 in order to determine whether there was a link between gestational weight gain (GWG), mothers' body mass index (BMI), and infant mortality. The women in the study responded to telephone or written questionnaires within nine months after their babies' birth, and their information was recorded in the Pregnancy Risk Assessment Monitoring System (PRAMS) for use by future researchers. The study team analyzed the PRAMS data to learn whether mothers' BMI before and during pregnancy might alter the influence of GWG on infant mortality.
Infant mortality risks in the study sample were 3.9% among infants of mothers who gained an inadequate amount of weight during pregnancy, 1.2% among infants of mothers who gained an adequate amount of weight, and .7% among mothers who gained more than the recommended amount. Mothers' pre-pregnancy BMI was also a key factor in infant survival. Mothers who were underweight before pregnancy and gained too little weight during pregnancy had six times the normal rate of infant mortality. Even among overweight women, inadequate weight gain was associated with a two-fold elevation in the risk of mortality. Only children born to obese women were protected from the effects of inadequate weight gain. In contrast, gaining more than the recommended amount of weight was not associated with risk to the infant among mothers in any weight category. Obese mothers who gained an excessive amount of weight actually had a 49% reduced likelihood of infant death.
This study confirms that only about a third of women in the US gain weight during pregnancy that is within the recommended range. In order to improve the likelihood of healthy outcomes for mothers and infants, healthcare providers should provide childbearing women with gestational weight gain goals that are specific to their individual BMI. Pregnant women can help ensure the health of their infants by monitoring their weight gain, eating an appropriate amount of healthy foods, and engaging in reasonable physical activity.
Tuesday, December 17, 2013
Paracetamol (acetaminophen) is the most commonly used medicine in pregnancy, yet there are very few studies that have investigated the possible long-term consequences for the child. A new study from the Norwegian Institute of Public Health suggests that long-term use of paracetamol during pregnancy may increase the risk of adverse effects on child development.
The study uses data from the Norwegian Mother and Child Cohort Study to investigate the effect of paracetamol during pregnancy on psychomotor development, behaviour and temperament at 3 years of age. Almost 3000 sibling pairs were included in the study.
The study is a collaboration between the University of Oslo, the Norwegian Institute of Public Health and the Hospital for Sick Children in Toronto, Canada, and was published in the International Journal of Epidemiology 25th October 2013.
By comparing children who were exposed to paracetamol during pregnancy with unexposed siblings of the same sex, researchers could control for a variety of genetic and environmental factors, in addition to other important factors such as infections, fever, use of other medications, alcohol intake and smoking.
• The study shows that children who had been exposed to paracetamol for more than 28 days of pregnancy had poorer gross motor skills, poor communication skills and more behavioural problems compared with unexposed siblings.
• The same trend was seen with paracetamol taken for less than 28 days, but this was weaker.
• To investigate whether the underlying illness could be the cause of the effect on the children, and not paracetamol itself, the researchers examined a different type of analgesic with another type of mechanism of action (ibuprofen). The researchers did not find any similar long-term effects after use of ibuprofen.
Monday, December 16, 2013
Enduring the last few weeks of pregnancy can be physically and emotionally challenging for some women. The aches and pains, the swelling of the limbs and the anxiety of when labor may start are part of the natural gestation process, but they also can seem unbearable. It may seem easier to relieve symptoms associated with late pregnancy by electing to deliver early, but Mayo Clinic researchers caution that there can be an increased risk of complications to the mother and the newborn associated with early-term deliveries.
Mayo researchers recently published a review article on this topic in the journal Mayo Clinic Proceedings.
Historically, a full-term pregnancy is calculated as 40 weeks after the last menstrual period. A term pregnancy occurs at 37 weeks or beyond, and an early-term pregnancy is considered to be 37 weeks to 38 weeks and six days. According to the researchers, approximately 10 to 15 percent of all deliveries in the United States are performed before 39 completed weeks of gestation without a true medical indication for early delivery.
"Morbidity and mortality rates have increased in mothers and their babies that are born in the early-term period compared to babies born at 39 weeks or later," says Jani Jensen, M.D., obstetrician and lead author of the study. "There is a need to improve awareness about the risks associated with this."
The increased risks for newborns include morbidity, such as respiratory (breathing) difficulties, feeding difficulties and problems such as cerebral palsy although the overall risk is low. These morbidities can also lead to higher rates of admission to the neonatal intensive care unit (NICU).
An elective early-term delivery requires a pregnant woman to be induced, which involves medication or procedures to help start labor. This can lead to a prolonged labor requiring deliveries with instruments such as forceps or a vacuum and may cause infection or hemorrhaging. There is also an increased risk of needing to have a cesarean delivery, and long term there could be more surgical complications for the mother. "It's not an entirely benign procedure that we are talking about," says Dr. Jensen.
Dr. Jensen sees a huge need to increase patient awareness and the public's perception about term pregnancy and when it is safe to deliver a baby. One research study that was reviewed included 650 women who recently delivered a baby. Half of the respondents believed that a full-term pregnancy occurred at 37 to 38 weeks of gestation and 25 percent thought it was safe to deliver a baby at 34 to 36 weeks.
Smoking tobacco or marijuana, taking prescription painkillers, or using illegal drugs during pregnancy may increase the risk of stillbirth, according to a new study.
Stillbirth occurs when a fetus dies at or after 20 weeks of gestation. While the U.S. stillbirth rate decreased from 18 per 1,000 births in 1950 to 6 per 1,000 births in 2006, it still remains higher than many other developed countries and affects almost 26,000 U.S. newborns each year.
To learn more about the causes and prevention of stillbirth, NIH created the Stillbirth Collaborative Research Network. With support from NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the network enrolled more than 600 women who delivered stillbirths at 59 participating hospitals. For comparison, the scientists also enrolled almost 2,000 women who gave birth to a live infant.
The researchers took umbilical cord and blood samples at delivery from the 2 groups of women. They tested the women’s blood for cotinine, a derivative of nicotine. They tested the umbilical cords for evidence of the stimulants cocaine and amphetamine; prescription painkillers, such as morphine and codeine; and marijuana. They also asked the women to self-report smoking and drug use during pregnancy. The results appeared online on December 6, 2013, in Obstetrics & Gynecology.
Among the women who experienced a stillbirth, about 19% showed traces of cotinine and about 7% tested positive for other drugs. In comparison, among women who gave birth to a live infant, about 9% tested positive for cotinine and 4% for other drugs.
Based on blood test results and the women’s responses, the researchers estimated that tobacco use increased the risk of stillbirth by 1.8 to 2.8 times, with the highest risk found among those with the highest cotinine levels. Women who reported they didn’t smoke but tested positive for cotinine (and so were presumably exposed to second-hand smoke) had roughly double the risk of stillbirth.
Women with stillbirth were twice as likely as those with a live birth to report having been addicted to an illicit drug. A positive test for any drug in the umbilical cord was also associated with about double the risk for stillbirth. However, the researchers couldn’t entirely separate the effects of smoking tobacco from those of smoking marijuana. In addition, the number of women who tested positive for stimulant or prescription painkiller use was small. Further study will be needed to understand the effects of these drugs on stillbirth.
With the legalization of marijuana in some states and the continued widespread use of other drugs, these findings highlight the need for preventing drug and tobacco use during pregnancy.
“Smoking is a known risk factor for stillbirth, but this analysis gives us a much clearer picture of the risks than before,” says senior author Dr. Uma M. Reddy of NICHD. “Additionally, results from the latest findings also showed that likely exposure to secondhand smoke can elevate the risk of stillbirth.”
Thursday, December 12, 2013
Pregnant women and women planning to become pregnant can make use of the holiday season to adjust their diets and reduce the risk of gestational diabetes, according to researchers at the University of Adelaide's Robinson Institute.
The recommendation comes at a time when there is increasing evidence to suggest that red meat is linked with a higher rate of gestational diabetes in pregnant women, which poses risks to the health of both the mother and the baby.
In a commentary published in this month's journal Evidence-Based Nursing, author Philippa Middleton says the latest international research shows that women who eat a lot of red and processed meats even before they become pregnant have a significant risk of developing gestational diabetes.
"There have been several reports linking red meat with increased risk of type 2 diabetes, and now the work of a number of research teams worldwide is showing this link for diabetes during pregnancy," says Ms Middleton, who is one of the Robinson Institute's research leaders.
"While this news is alarming, there are also some positives. The latest research from the United States has shown that eating fish and poultry does not increase the risk of gestational diabetes, and consuming more vegetable and non-meat protein is associated with a reduction in risk.
"For example, just over half a serving of nuts per day can reduce the risk of gestational diabetes by 40%."
Ms Middleton says although the link between red meat and diabetes is strengthening, scientists still don't understand the underlying mechanisms that cause it.
"More research is needed to better understand why this is happening and how to adapt women's diets and other lifestyle behaviors to prevent both gestational and type 2 diabetes," she says.
"Based on current evidence, pregnant women or women planning to become pregnant should consider eating more vegetable protein, and nuts, and replacing some red meat with fish and poultry.
"Midwives, dieticians and others involved in pregnancy care can help women to make these dietary changes in the hope of reducing poor outcomes for the mother and the baby," Ms Middleton says.