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Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

WHO International Clinical Trials Registry Platform

The World Health Organization (WHO) has created a new Web site to help researchers, doctors and
patients obtain reliable information on high-quality clinical trials. Now you can go to one website and search all registers to identify clinical trial research underway around the world!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

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Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.
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No dirivative works may be made or used for commercial purposes.


Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
Google Search artcles published since 2007

Home | Pregnancy Timeline | News Alerts |News Archive Feb 18, 2014


PM2.5 is a measurement of small particulate matter in the air. China plans to begin
regulating PM2.5 within five years and set binding targets to reduce the fine particles
between 2015 and 2020. Coal consumption and vehicle exhaust are the major causes,
of China's air pollution. But different regions contribution to the pollution varies.

Image Credit: Green Peace, East Asia

WHO Child Growth Charts




Air pollution increases risk for preeclampsia

Breathing the air outside their homes may be just as toxic to pregnant women — if not more so — as breathing in cigarette smoke, increasing a mom-to-be’s risk of developing deadly complications such as preeclampsia, according to findings from a new University of Florida study.

University of Florida (UF) researchers compared birth data with Environmental Protection Agency estimates of air pollution, finding that heavy exposure to four air pollutants led to a significantly increased risk for developing a high blood pressure disorder during pregnancy. The research was published in the January issue of the Journal of Epidemiology & Community Health.

The pollutants include two specific types of fine and coarse particulate matter, carbon monoxide and sulfur dioxide. According to the EPA, particulate matter includes acids, dust, metals and soil particles. These inhalable particles are released from industries and forest fires and can form when gases react with each other in the air. Sulfur dioxide is emitted from power plants and industries. Most carbon monoxide is produced by car exhaust.

“Fetal development is very sensitive to environmental factors.That is why we wanted to do this research. Hypertension (high blood pressure), in particular, is associated with increased morbidity and mortality, causing a lot of problems for the mother and fetus, including preterm delivery.”

Xiaohui Xu, M.D., Ph.D., assistant professor of epidemiology in the colleges of Public Health and Health Professions and Medicine.

Hypertensive disorders such as gestational hypertension, preeclampsia and the deadly condition it leads to, eclampsia, affect about 10 percent of pregnancies. Despite the serious risks to mother and baby, little was known about what specifically causes these conditions to develop in pregnant women.

To gain an understanding of how environment plays a role in the risk of developing hypertension during pregnancy, researchers examined data from more than 22,000 pregnant women in Jacksonville, Fla., who gave birth between 2004 and 2005 along with environmental data from their communities.

The research sample only included mothers without chronic hypertension, those who had never given birth prematurely, nor any women whose babies were born with complications. They then gauged how much pollution the women were exposed to throughout their pregnancies using data the EPA gathered daily to measure the levels of several pollutants.

Among the 22,000 women, 4.7 percent developed a hypertensive disorder during pregnancy. After controlling for socioeconomic status, exposure to co-pollutants and smoking during pregnancy, it was determined that air pollutant exposure throughout the first two trimesters of pregnancy increased women’s risk for developing hypertension.

“It looks like the whole period has impacts for hypertension,” he said.

On the basis of these findings, researchers believe more air pollution control is necessary to prevent dangerous complications in pregnant women and their babies. Although more studies are needed, researchers believe exposure to air pollution during pregnancy may affect a woman’s normal pattern of blood pressure.

Next, the researchers plan to expand their study throughout the state and examine other health conditions that may be affected by pollution. “We want to look at preterm delivery and low birth-weight and find out what the effects of breathing contaminated air are on fetal development,” Xu added.

Background Ambient air pollution has been implicated in the development of hypertensive disorders of pregnancy (HDP). However, evidence of the association between air pollution and HDP is still limited, and the effects of gaseous air pollutants on HDP and their time windows of exposure have not been well studied.

Methods We used the Florida birth registry data to investigate the associations between air pollutants (NO2, SO2, PM2.5, O3 and CO) and the risks of HDP in 22 041 pregnant women in Jacksonville, Florida, USA from 2004 to 2005. Further, we examined whether air pollution exposure during different time windows defined by trimesters and the entire pregnancy had different effects on HDP.

Results The single-pollutant logistic regression model showed that exposure to four pollutants during the full pregnancy period was significantly associated with prevalence of HDP after adjusting for covariates: NO2 (OR=1.21, 95% CI 1.09 to 1.35), PM2.5 (OR=1.24, 95% CI 1.08 to 1.43), SO2 (OR=1.13, 95% CI 1.01 to 1.25) and CO (OR=1.12, 95% CI 1.03 to 1.22) per IQR increase. Similar effects were observed when first trimester exposure to NO2, SO2 and CO, and second trimester exposures to PM2.5 were examined. Consistent results were confirmed in multiple-pollutant models.

Conclusions This study suggests that exposure to high levels of air pollution during early pregnancy and the full gestational period was associated with increased prevalence of HDP in Florida, USA.

Xiaohui Xu, Hui Hu, Sandie Ha, Jeffrey Roth

Received 27 May 2013
Revised 21 July 2013
Accepted 29 July 2013
Published Online First 10 September 2013

The research was funded through grant K01ES019177 from the National Institute of Environmental Health Sciences.