Welcome to The Visible Embryo
The Visible Embryo Birth Spiral Navigation
Fetal Timeline--- -Maternal Timeline-----News-----Prescription Drugs in Pregnancy---- Pregnancy Calculator----Female Reproductive System

WHO International Clinical Trials Registry Platform

The World Health Organization (WHO) has a Web site to help researchers, doctors and patients obtain information on clinical trials.

Now you can search all such registers to identify clinical trial research around the world!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System


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.

Content protected under a Creative Commons License.
No dirivative works may be made or used for commercial purposes.


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

Brain Development

Air pollution linked to brain alteration

For the first time a relationship is identified between exposure to air pollution and lack of inhibition control...

A joint study performed by the Barcelona Institute for Global Health (ISGlobal) and the Erasmus University Medical Center of Rotterdam, links residential air pollution during fetal life to brain abnormalities. These abnormalities may contribute to impaired cognitive function seen in school-age children. The study details how air pollution levels now considered safe, are related to alterations of the brain. The work is published in Biological Psychiatry

The study revealed a relationship between exposure to air pollution and difficulty with the inhibition control center in the brain — impulsive behavior related to mental health problems such as addictions and attention-deficit/hyperactivity disorder. A fetus exposed to fine particles may develop a thinner cortex — the outer layer of the brain — in several areas and/or on both brain hemispheres that may explain impairment in that individual's inhibition control later in life.

A population-based cohort study conducted in the Netherlands, enrolled 783 newly pregnant women and then followed their births and those children through school age. Researchers began by assessing the air pollution levels at the women's homes during their pregnancies. This data was collected via air pollution monitoring campaigns of nitrogen dioxide levels, as well as course and fine particulate matter being breathed. Researchers later took brain morphology images of the children when they reached 6 to 10 years old to assess brain development.
The relationship between fine particle exposure, brain structure alteration, and inhibition control was found despite the fact that the average residential levels of fine particles in the study were well below the current European Union (EU) limit.

Only 0.5% of the pregnant women in the study were exposed to levels considered unsafe. The average residential levels of nitrogen dioxide were right at the safe limit.

This finding adds to previous studies that link what government regulations consider to be "acceptable air pollution levels" to other birth complications including cognitive decline and problems in fetal growth. The fetal brain is particularly vulnerable as it hasn't yet developed mechanisms to protect against or remove environmental toxins.
"Although specific individual clinical implications of these findings cannot be quantified, based on other studies, the observed cognitive delays at early ages could have significant long-term consequences such as increased risk of mental health disorders and low academic achievement, in particular due to the ubiquity of the exposure. Therefore, we cannot warrant the safety of the current levels of air pollution in our cities."

Mònica Guxens MD, MPH, PhD, Barcelona Institute for Global Health (ISGlobal); Pompeu Fabra University, Barcelona, Spain; Spanish Consortium for Research on Epidemiology and Public Health, Instituto de Salud Carlos III, Madrid, Spain; Department of Child and Adolescent Psychiatry/Psychology, Erasmus University Medical Centre–Sophia Children’s Hospital, Rotterdam, The Netherlands.


Air pollution exposure during fetal life has been related to impaired child neurodevelopment, but it is unclear if brain structural alterations underlie this association. The authors assessed whether air pollution exposure during fetal life alters brain morphology and whether these alterations mediate the association between air pollution exposure during fetal life and cognitive function in school-age children.

We used data from a population-based birth cohort set up in Rotterdam, The Netherlands (2002–2006). Residential levels of air pollution during the entire fetal period were calculated using land-use regression models. Structural neuroimaging and cognitive function were performed at 6 to 10 years of age (n = 783). Models were adjusted for several socioeconomic and lifestyle characteristics.

Mean fine particle levels were 20.2 ?g/m3 (range, 16.8–28.1 ?g/m3). Children exposed to higher particulate matter levels during fetal life had thinner cortex in several brain regions of both hemispheres (e.g., cerebral cortex of the precuneus region in the right hemisphere was 0.045 mm thinner (95% confidence interval, 0.028–0.062) for each 5-?g/m3 increase in fine particles). The reduced cerebral cortex in precuneus and rostral middle frontal regions partially mediated the association between exposure to fine particles and impaired inhibitory control. Air pollution exposure was not associated with global brain volumes.

Exposure to fine particles during fetal life was related to child brain structural alterations of the cerebral cortex, and these alterations partially mediated the association between exposure to fine particles during fetal life and impaired child inhibitory control. Such cognitive impairment at early ages could have significant long-term consequences.

Authors: Mònica Guxens, Ma?gorzata J. Lubczy?ska, Ryan L. Muetzel, Albert Dalmau-Bueno, Vincent W.V. Jaddoe, Gerard Hoek, Aad van der Lugt, Frank C. Verhulst, Tonya White, Bert Brunekreef, Henning Tiemeier, Hanan El Marroun.

The Barcelona Institute for Global Health (ISGlobal) is supported by the "la Caixa" Foundation.

Return to top of page

Mar 13, 2018   Fetal Timeline   Maternal Timeline   News   News Archive

Different brain regions affected by fine and coarse particles.
Image credit: ISGlobal / Biological psychiatry.

Phospholid by Wikipedia