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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


How to prevent asthma in your newborn?

The best way to reduce a child's chances of developing asthma might be to make sure mom has enough vitamin D during her second trimester of pregnancy.

According to a new study from the University of Kansas, the most cost-effective way to get mothers more vitamin D could be as simple as soaking up a little more sun. The research will appear in a new publication: the American Journal of Health Economics.

According to the Centers for Disease Control and Prevention, 1 in 12 people in the U.S.A. suffers from asthma.

"Our health system spends billions and billions treating asthma, and there's lots and lots of opportunity costs," said David Slusky, assistant professor of economics at the University of Kansas (KU). "Pain and suffering, loss of productivity and premature death — asthma has it all."

When resources are being used inefficiently, that's when Slusky and his fellow economists step in. They were aware of the recent medical hypothesis by Scott Weiss and Augusto Litonjua, both physicians at Brigham and Women's Hospital in Boston and professors at Harvard Medical School. The physicians hypothesized that vitamin D levels in the second trimester of pregnancy influence probability a fetus will develop asthma later in life.

Slusky and Nils Wernerfelt of the Massachusetts Institute of Technology along with Richard Zeckhauser of Harvard's Kennedy School, tested the medical hypothesis using an economist's tools — surveys and health data.

"This is a golden age for data. Hospital discharges, insurance claims, birth certificates and death certificates are more and more available and more and more set up for research. This allows economists to get really large sample sizes with not a lot of cost."

David Slusky, Assistant Professor Economics, University of Kansas

Using data from hospital discharges in two states and from a national survey, Slusky and his colleagues looked at where and when asthmatics were born. Then they collected measurements of sunlight at those locations, specifically when mothers would have been in their second trimesters. Sunlight is where Americans get more than 90 percent of our vitamin D.

What the economists found was that a mother's increased sunlight exposure — and consequently vitamin D level — during her second trimester lowers her child's chance of developing asthma. To address concerns about possible systemic differences between individuals from different parts of the country, the co-authors considered relative differences. "We were not looking at sunny places versus non-sunny places," Slusky explained "We looked at the relative differences of the level of sunlight at a particular place at a particular time of year." In other words, people born in Georgia in July of 1978 received a different exposure to sunlight in utero than did Georgians born a year later.

Slusky: "If that place is relatively more sunny during the second trimester, we found relatively lower rates of asthma."

The findings indicate that the way pregnant women can get more vitamin D — and lessen the likelihood of asthma in their children — may be as simple as 10 minutes in the sun, which medical literature indicates is all most of us need for a daily dose of the "sunshine vitamin."

"Skin cancer is a very serious disease, and I don't want to minimize it, but at some point that extra minute you spend inside is costing you more vitamin D than it's helping you not get skin cancer," Slusky said.

Vitamin D can be acquired from dietary supplements, too, but Slusky and his colleagues point out that the prenatal vitamins many pregnant women take already include vitamin D and that they may not be getting the full benefit from them.

Moreover, sunshine is free.

"Calibrating this into the proper policy recommendation is something I'll leave to others, but I think that's where this research is going," Slusky said.

Case in point, health officials in Australia are becoming more aware of vitamin D deficiencies. They have begun urging schools to relax requirements that students wear hats while outside during that continent's winter months of June and July.

"Clearly if I'm going to the beach or going to spend all day outside, I need to put on sunscreen," Slusky said. "But spending 10 minutes outside without it may not be such a bad idea."

This research explores the role of sunshine in birth outcomes production, focusing primarily on fetal growth. The most obvious mechanism is through vitamin D absorption, which could explain racial disparities in birth weight because skin pigmentation inhibits this process. However, sunshine may have additional effects and is closely connected to environmental factors, season of birth, and geography. Combining daily weather data with 1989–2004 birth outcomes from the Natality Detail Files, we estimate sunshine's effects in a range of models that disentangle these confounding factors. Our results suggest that sunshine has a positive but diminishing effect on birth weight for blacks and a negative effect for whites. These findings are consistent with the presumed positive but diminishing effects of sunshine via vitamin D balanced against the possible negative effects via folic acid depletion and immune system impairment. The estimated magnitudes are in line with those found for other key factors such as feeding programs and air pollution and suggest that sunshine's effects explain a nontrivial portion of racial differences in birth weight. Implications include possible interventions (vitamin supplementation for blacks, sun avoidance for whites) and the need to include sunshine as a potentially important factor in birth outcomes research.

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Apr 5, 2016   Fetal Timeline   Maternal Timeline   News   News Archive   

Economists found that a mother's increased sunlight exposure — and increased vitamin
D level — during her second trimester lowers her child's chance of developing asthma.

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