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	Women who are overweight and or obese during pregnancy may be at greater risk of preterm-and more notably-extremely preterm delivery, according to results of a new Swedish study published in 

	The purpose of the study was to assess early pregnancy body mass index (BMI) and preterm delivery risk by gestational age and by forerunners of preterm delivery.

	The population-based retrospective study focused on women with live singleton births in Sweden from 1992 to 2010. Data pertaining to the mothers as well as pregnancy factors were gathered from the Swedish Medical Birth Register. Preterm deliveries were classified as either extremely preterm (22-27 weeks); very preterm (28-31 weeks); or moderately preterm (32-36 weeks). In addition, the results were listed as either spontaneous (preterm contractions or premature rupture of membranes) or medically indicated preterm delivery (cesarean delivery before onset of labor or induced onset of labor).

	Risks were adjusted for the mother’s age, smoking, level of education, height, mother's country of birth, and year of delivery.

	The results showed that for 1,599,551 deliveries that had data on early pregnancy BMI, 3082 fell into the “extremely preterm” category, 6893 were “very preterm,” and 67,059 were “moderately preterm.” As BMI increased, so did risks of extremely, very, and moderately preterm deliveries; further, overweight and obesity-specific risks were highest for extremely preterm delivery.

	“Considering the high morbidity and mortality among extremely preterm infants, even small absolute differences in risks will have consequences for infant health and survival,” the authors said in a statement. “Even though the obesity epidemic in the U.S. appears to have leveled off, there is a sizable group of women entering pregnancy with very high BMI.”

	For women of normal weight (BMI 18.5 to <25), extremely preterm delivery rate was 0.17%. Compared to women of normal weight, rates (%) of extremely preterm delivery were: BMI 25 to <30 (0.21%), BMI 30 to <35 (0.27%), BMI 35 to <40 (0.35%), and BMI of ≥40 (0.52%). For obese women (BMI ≥30), risk of spontaneous extremely preterm delivery was elevated. Risks of medically indicated preterm deliveries also increased with BMI among overweight and obese women.

	For more on the risks associated with obesity during pregnancy, see this month’s cover story on page 26.

	Cnattingius S, Villamor E, Johansson S, et al. Maternal obesity and risk of preterm delivery. 

Articles

Overweight, obese pregnant women have higher risk of very early delivery

	Three major Ohio universities and 4 hospitals have joined with the March of Dimes Foundation to establish a new collaborative research program aimed exclusively at finding the unknown causes of premature birth. The March of Dimes intends to invest $10 million in the program over 5 years.

 Editor-in-Chief Charles J. Lockwood, MD, MHCM, is the Dean of the College of Medicine and Vice President for Health Sciences at Ohio State University, one of the institutions in the collaborative. Editorial Board member Joe Leigh Simpson, MD, is senior vice president of research and global programs for the March of Dimes.

	“In some ways, for prematurity researchers, Ohio is kind of the promised land and this is the golden age,” Dr. Lockwood told 

. Research into Ohio’s Somali population, for example, could prove enlightening, since Somali women have lower rates of prematurity than African-American women, who have extremely high rates, he said.

	According to the March of Dimes, 1 in 9 children born in the United States arrives before 37 weeks’ gestation. In Ohio, 1 in 8-or more than 15,000 babies-is born early each year.

	Partners in the research collaborative include:

	• University of Cincinnati College of Medicine and Cincinnati Children’s Hospital Medical Center;

	• The Ohio State University Wexner Medical Center and Nationwide Children’s Hospital, Columbus; and

	• Case Western Reserve University; University Hospitals’ MacDonald Women’s Hospital and Rainbow Babies & Children’s Hospital; and MetroHealth System, all of Cleveland.

	The 5 focuses of research over the next 5 years are: the evolution of human pregnancy, the genetics of unique human populations, the molecular developmental biology of pregnancy, progesterone signaling in pregnancy maintenance and preterm birth, and the sociobiology of racial disparities in preterm birth.

Three major Ohio universities and 4 hospitals have joined with the March of Dimes Foundation to establish a new collaborative research program aimed exclusively at finding the unknown causes of premature birth.

Major prematurity research collaborative launched in Ohio

	One in 3 women nulliparous women with a short cervix is prescribed some type of activity restriction, despite lack of benefit in prevention of preterm birth (PTB). Those are the findings from a secondary analysis of data from the Short Cervix and Nulliparity trial. Published in 

, it is accompanied by a commentary titled “

Bed Rest in Pregnancy: Time to Put the Issue to Rest

ethical argument for dismissing the practice

	In the Short Cervix and Nulliparity trial, asymptomatic nulliparas with singleton gestations and cervices <30 mm were randomized to either weekly intramuscular 17-α hydroxyprogesterone caproate or placebo. The secondary analysis looked at the women’s responses to weekly questions about whether they had been placed on pelvic, work, or nonwork rest.

	Of the 657 women in the trial, 646 (98%) responded to the activity restriction questions and 252 (39% were placed on any activity restriction at median of 23.9 weeks (interquartile range 22.6-27.9 weeks). Activity restriction was more likely to be prescribed if a woman was older (

<.001), or had funneling and intra-amniotic debris. PTB at <37 weeks was more common in those who were placed on activity restriction (37% vs 17%, 

<.001). PTB remained more common in the activity restriction group even after the investigators controlled for potential confounding factors (adjusted odds ratio 2.37; 95% CI, 1.60-3.53). Similar results were seen for PTB at <34 weeks’ gestation.

	The authors note that activity restriction “was not always more likely to be prescribed to women with characteristics most associated with preterm birth” and that it is “dependent not only on the perception of risk status, but on social factors as well.” Their analysis, they conclude, “emphasizes the importance of conducting an adequately powered randomized trial for women at increased risk of preterm birth such that level I evidence for the effects of activity restriction can be obtained.”

One in 3 women nulliparous women with a short cervix is prescribed some type of activity restriction, despite lack of benefit in prevention of preterm birth (PTB). Those are the findings from a secondary analysis of data from the Short Cervix and Nulliparity trial. Published in Obstetrics & Gynecology, it is accompanied by a commentary titled “Bed Rest in Pregnancy: Time to Put the Issue to Rest” and an ethical argument for dismissing the practice.

Does bed rest prevent preterm birth?

Maternal-fetal exchange of cells may result in deposition of  male DNA to the mother’s brain that lasts a lifetime and has potential health  effects. So say the results of a study published in 

 of autopsied brain tissue  from women aged 32 to 101 without neurologic disease or with Alzheimer’s  disease.

Of the 59 brain autopsy specimens analyzed with real-time  quantitative polymerase chain reaction (PCR) by researchers from the University  of Washington, Seattle, 37 (63%) harbored microchimerism (Mc)-cells from a  genetically distinct organism, in this case, a male. The DNA was found in  multiple brain regions and highest in the medulla but absent from the frontal  lobe and putamen. Of the 9 women known to have borne at least 1 son, 5 had male  DNA in at least 1 brain region, all of whom had Alzheimer’s. The cells also  were found in 1 of 2 women with no history of delivering sons, who had no  history of neurologic disease.

=0.06) of male  DNA in the brains of women with Alzheimer’s were lower than in women without  neurologic disease. Analysis of specimens only from the five brain regions  believed to be most affected by Alzheimer’s showed that odds of having the  disease were 52% lower for those with male DNA than without it, despite the  fact that Alzheimer’s is more prevalent in women than in men.

The researchers believe their study is the first of male DNA  in women’s brains and specific brain regions and that further investigation is  needed of the health implications, particularly given the unexpected results  related to Alzheimer’s. The findings, they say, show that “fetal DNA and likely  cells can cross the human blood-brain barrier (BBB) and reside in the brain.”  Potential sources of male DNA, they postulate, include an abortion,  miscarriage, male twin, older male sibling, or a non-irradiated blood  transfusion. According to the investigators, however, “the most likely source  of male Mc in female brain is acquisition of fetal Mc from pregnancy with a  male fetus.” 

Maternal-fetal exchange of cells may result in deposition of male DNA to the motherâ€™s brain that lasts a lifetime and has potential health effects. So say the results of a study published in PLoS One of autopsied brain tissue from women aged 32 to 101 without neurologic disease or with Alzheimerâ€™s disease.

Author | Contemporary OB/GYN Staff

Articles

Overweight, obese pregnant women have higher risk of very early delivery

Major prematurity research collaborative launched in Ohio

Does bed rest prevent preterm birth?

DNA from Male Fetus May Alter Maternal Brain