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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.

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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

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Home | Pregnancy Timeline | News Alerts |News Archive May 26, 2015

Obesity in pregnancy may increase chances for having a child with autism.





Mom's obesity compromises infant immune system

When exactly does the immune system of babies born to obese mothers get compromised? Very early, according to a new study from the University of California, Riverside.

The team led by Ilhem Messaoudi PhD, analyzed umbilical cord blood from infants born to lean, overweight and obese mothers. They found that pre-pregnancy weight has a significant impact on the immune system of the neonate, putting them at risk for potential risks of heart disease and asthma.

The pilot study, performed on 39 mothers in Portland, Ore., is published online in the journal Pediatric Allergy and Immunology. The UC Riverside-led study investigated key innate and adaptive immune cells in umbilical cord blood samples collected from babies born to lean, overweight and obese mothers

Almost 60 percent of women of childbearing age in the United States are overweight or obese — a major public health issue which has been linked to heart disease, cancer and hypertension. It can complicate pregnancy by increasing the mother's risk for gestational diabetes, preeclampsia and preterm birth. Maternal obesity is also linked to an infant's risk for birth defects, type-2 diabetes, heart disease and even death.

"A number of studies have linked maternal obesity - starting pregnancy with excess weight and gaining a lot of weight during pregnancy - to a higher incidence of cardiovascular disease and asthma ... potential links between changes in the offspring's immune system and increased susceptibility of these diseases later in life."

Ilhem Messaoudi PhD, associate professor, Bbiomedical Sciences, School of Medicine, University of California at Riverside.

Researchers used body mass index (BMI) to sort moms participating in the study by calculating BMI based on height and weight. A woman was considered overweight if her BMI was 25 to 29.9, and obese if her BMI was 30 or higher. All moms were non-smoking, without diabetes and had an uncomplicated gestation at term delivery of just one baby. Eleven mothers were lean, 14 were overweight, and 14 were obese. Thirty were white, three were Asian American/Pacific Islander, one was an American-Indian/Alaskan native, and two were African American. The racial identity of three was unknown.

"We found that very specific immune cells — monocytes and dendritic cells — isolated from babies born to moms with a high BMI, were unable to respond to bacterial antigens when compared to babies born to lean moms. Obese mom babies also showed a reduction in 'CD4 T-cells.' Both of these changes could result in compromised responses to infection and vaccination," said Ilhem Messaoudi PhD.

Researchers also found that cells that play a role in allergic response and asthma — eosinophil cells —were significantly less in number in the umbilical cord blood of babies of obese moms.

One possible explanation for both observations is that eosinophil cells moved into the lungs, explaining an increased incidence of asthma later in life in children born to obese mothers.

This research is the first to reveal a link between obesity during pregnancy and neonatal immunity. It also reveals changes in immunity are detectable at birth — which could persist for a lifetime, from infancy into adulthood.

Messaoudi believes: "This could change how we respond to vaccination and how we respond to asthma-inducing environmental antigens. We know, in the first two years of life, children typically receive plenty of vaccines. The questions then arise: (1) Are the responses to vaccines of infants born to obese moms also impaired in the first two years of life? (2) Should we change how often we vaccinate children born to obese moms? (3) Should we change practices of how many and how often we vaccinate?"

Messaoudi feels this research paper is a launching point for further studies and a call to action.

"If you are thinking of becoming or are already pregnant, talk to your ob-gyn about weight management, weight gain and the ideal targets for weight gain.When moms come in for prenatal visits, doctors tell them about smoking, recreational drug use, and alcohol. But they should be talking also about weight and weight management.

"Obesity has serious repercussions for maternal health. It is associated with low fertility and low success with pregnancy. Rates of gestational diabetes, preeclampsia, placental abruption - all increase dramatically with weight gain and obesity. So it is important to talk to your doctor about ideal weight entering into pregnancy and [maintained] throughout pregnancy."

Ilhem Messaoudi PhD

Maternal obesity is one of several key factors thought to modulate neonatal immune system development. Data from murine studies demonstrate worse outcomes in models of infection, autoimmunity, and allergic sensitization in offspring of obese dams. In humans, children born to obese mothers are at increased risk for asthma. These findings suggest a dysregulation of immune function in the children of obese mothers, however, the underlying mechanisms remain poorly understood. The aim of this study was to examine the relationship between maternal body weight and the human neonatal immune system.

Umbilical cord blood samples were collected from infants born to lean, overweight, and obese mothers. Frequency and function of major innate and adaptive immune cell populations were quantified using flow cytometry and multiplex analysis of circulating factors.

Compared to babies born to lean mothers, babies of obese mothers had fewer eosinophils and CD4 T helper cells, reduced monocyte and dendritic cell responses to toll-like receptor ligands, and increased plasma levels of IFNα2 and IL-6 in cord blood.

These results support the hypothesis that maternal obesity influences programming of the neonatal immune system, providing a potential link to increased incidence of chronic inflammatory diseases such as asthma and cardiovascular disease in the offspring. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.

Messaoudi was joined in the study by Randall M. Wilson and Daniel R. Jeske at UCR; and Nicole E. Marshall, Jonathan Q. Purnell and Kent Thornburg at the Oregon Health & Science University, Portland, Ore.

The research was supported by grants from the National Institutes of Health.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion. A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. UCR also has ISDN for radio interviews. To learn more, call (951) UCR-NEWS.

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