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Pregnancy Timeline by SemestersDevelopmental TimelineFertilizationFirst TrimesterSecond TrimesterThird TrimesterFirst Thin Layer of Skin AppearsEnd of Embryonic PeriodEnd of Embryonic PeriodFemale Reproductive SystemBeginning Cerebral HemispheresA Four Chambered HeartFirst Detectable Brain WavesThe Appearance of SomitesBasic Brain Structure in PlaceHeartbeat can be detectedHeartbeat can be detectedFinger and toe prints appearFinger and toe prints appearFetal sexual organs visibleBrown fat surrounds lymphatic systemBone marrow starts making blood cellsBone marrow starts making blood cellsInner Ear Bones HardenSensory brain waves begin to activateSensory brain waves begin to activateFetal liver is producing blood cellsBrain convolutions beginBrain convolutions beginImmune system beginningWhite fat begins to be madeHead may position into pelvisWhite fat begins to be madePeriod of rapid brain growthFull TermHead may position into pelvisImmune system beginningLungs begin to produce surfactant
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development


Risk factors for preterm birth can be changed

A significant portion of preterm births might be avoided by reducing or eliminating any one of three major risk factors.

A new Cincinnati Children's Hospital Medical Center study shows that as many as 25 percent of preterm births might be attributed to (1) the shortness of space between pregnancies, (2) the mother's body mass index prior to pregnancy, and (3) the amount of weight gained during pregnancy. All of these risk factors can be modified to reduce the risk of premature births — which is any birth which occurs before 37 weeks gestation.

The study is published online in the Maternal and Child Health Journal.

"The highest risks for premature birth were in women who were underweight, had poor weight gain during pregnancy, or short periods of time between pregnancies," says Emily DeFranco, DO, a physician-researcher at the Center for Prevention of Preterm Birth at Cincinnati Children's and an associate professor of maternal-fetal medicine at the University of Cincinnati. "However, excessive weight gain in obese women also increases risk."

Ohio birth records from 2006 to 2011were studied of nearly 400,000 live, non-multiple births.

Potential risk factors for preterm birth were present in more than 90 percent of women in the study.

Fewer than half of women began pregnancy with a normal weight.

Only 32 percent of women achieved a recommended pregnancy weight gain.

"Attention should be paid to educational interventions on the importance of birth spacing, achieving an optimal pre-pregnancy weight, and ensuring adequate nutrition and weight gain during pregnancy," explained Dr. DeFranco. "Improvements in these modifiable risk factors could have significant influence on premature birth and infant mortality worldwide."

According to the March of Dimes, the rate of preterm birth in the United States is 12 percent — above the global average of 11.1 percent.

Objectives The purpose of this study is to evaluate the prevalence, impact, and interaction of short interpregnancy interval (IPI), pre-pregnancy body mass index (BMI) category, and pregnancy weight gain (PWG) on the rate of preterm birth. Methods This is a population-based retrospective cohort study using vital statistics birth records from 2006 to 2011 in OH, US, analyzing singleton live births to multiparous mothers with recorded IPI (n = 393,441). Preterm birth rate at <37 weeks gestational age was compared between the referent pregnancy (defined as normal pre-pregnancy maternal BMI, IPI of 12–24 months, and Institute of Medicine (IOM) recommended PWG) and those with short or long IPI, abnormal BMI (underweight, overweight, and obese), and high or low PWG (under or exceeding IOM recommendations). Results Only 6 % of the women in this study had a referent pregnancy, with a preterm birth rate of 7.6 % for this group. Short IPIs of <6 and 6–12 months were associated with increased rates of preterm birth rate to 12.9 and 10.4 %, respectively. Low PWG compared to IOM recommendations for pre-pregnancy BMI class was also associated with increased preterm birth rate of 13.2 % for all BMI classes combined. However, the highest rate of preterm birth of 25.2 % occurred in underweight women with short IPI and inadequate weight gain with adjOR 3.44 (95 % CI 2.80, 4.23). The fraction of preterm births observed in this cohort that can be attributed to short IPIs is 5.9 %, long IPIs is 8.3 %, inadequate PWG is 7.5 %, and low pre-pregnancy BMI is 2.2 %. Conclusions Our analysis indicates that a significant proportion of preterm births in Ohio are associated with potentially modifiable risk factors. These data suggest public health initiatives focused on preterm birth prevention could include counseling and interventions to optimize preconception health and prenatal nutrition.

Interpregnancy interval Body mass index Pregnancy weight gain Preterm birth

The research was funded in part by the March of Dimes.

About Cincinnati Children's
Cincinnati Children's, a non-profit, pediatric, academic medical center established in 1883, is internationally recognized for improving child health and transforming delivery of care through fully integrated, globally recognized research, education and innovation. It is one of the top three recipients of pediatric research grants from the National Institutes of Health, ranked third in the nation among all Honor Roll hospitals in U.S. News and World Report's Best Children's Hospitals, and a research and teaching affiliate of the University of Cincinnati's College of Medicine. Its patient population includes the eight-county primary service area covering parts of Ohio, Kentucky and Indiana. A destination for children with complex medical conditions, it also served patients from all 50 states and nearly 70 countries during the past year. Additional information can be found at http://www.cincinnatichildrens.org. Connect on the Cincinnati Children's blog, via Facebook and on Twitter.
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Aug 24, 2016   Fetal Timeline   Maternal Timeline   News   News Archive   

"The highest risks for premature birth were in women who were underweight, had poor
weight gain during pregnancy, or short periods of time between pregnancies."

Image Credit: Alamy Stock Photo



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