in nitro development Flashcards
the barker hypothesis
British Epidemiologist, Dr David Barker
* First to propose the foetal origins hypothesis (1986)
* Events during early development (in womb and
immediately after birth) have a big impact on the risk of
later developing adult diseases
* Coronary artery disease, hypertension, obesity, and
insulin resistance
* Much evidence gather
starts with altered maternal nutrition which results in an abnormal placenta (sensitive to nutrition) - altered foetal nutrition, which then leads to altered organ growth and maturation- particular organs that are compromised= heart, liver, pancreas, muscle, kidney= which then leads to conditions in adulthood
tetratogens
alcohol- Alcohol has been linked to a range of permanent birth defects, known as Fetal Alcohol Spectrum Disorder, which affect around 1% of babies born. It is a spectrum of disorders, the most severe being Fetal Alcohol Syndrome (FAS). This is associated with abnormal, distinct facial features, growth deficiencies, and problems with the brain and CNS, learning, memory, attention, communication, vision and hearing. Effects can occur in a dose-response relationship, but there is evidence that one binge can affect the embryo’s brain.
smoking- Another common teratogen is nicotine and other chemicals from smoking. 7.4% of women in England were known to be smokers at the end of their pregnancy in 2023-24 (NHS England, 2024),
although many others will be exposed through their partners who smoke. - The foetus receives all of its nutrients and oxygen via the mother’s placenta. The foetus receives nicotine and carbon monoxide from the mother, and as a product of this, also receives less
oxygen. Smoking during pregnancy is associated with increased chances of having a low birth weight or
premature baby and increased complications during pregnancy, including stillbirt
prescription- Prescription and medical drugs that are safe in general, are often not safe in pregnancy. A notable example is that of the drug thalidomide. This was given to pregnant women to help with morning sickness (between 1958-1961), but it had horrific effects on the foetus. Primarily affecting the limbs and organs, many babies were born missing limbs, with upper limbs more commonly affected than lower limbs. A critical period was identified; only those mothers taking the drug 4-6 weeks after conception (on the 20th- 34th days after fertilisation)- at the early stage in development when the limbs and organs are being formed - had babies with these deformities
maternal illness- All diseases are dangerous in pregnancy and so we try to guard against this. Rubella, measles and
chicken pox are particularly dangerous. Did you know that this is why young girls are
immunised against these diseases? So that if/when they do fall pregnant, they will not be at risk of contracting the virus and passing it to their child.
Rubella can do damage to the foetus even if contracted before a pregnancy starts. If the mother contracts Rubella in the month before conception, and up to 20 weeks gestation, there is a high threat of
miscarriage and a range of serious physical and developmental problems, including blindness, deafness, heart problems, learning difficulties and autism.
Mental illness has also been linked with maternal ill health during pregnancy and with critical
periods. Flu in the first trimester is associated with the development of schizophrenia (Brown et al.,
2004). However, this is likely to be a complex relationship that interacts with a range of other
factors and so causality should not be assumed.
malnutrition
Dutch famine study-Famine in utero
* Dutch “Hunger Winter” – 1944
* Mothers received around only 400kcal-800kcal per day. * Requirement is 2000-2200kcal. * Famine in early gestation – elevated obesity, altered lipid profiles,
cardiovascular disease, breast cancer (Rosebloom et al., 2001). * Also, age-associated decline in cognitive functioning (Rooij et al.,
2010). *
Recently research has started to explore the effect of
Ramadan fasting on pregnancy- some research indicates lower birth rate. however a review showed that Some studies found an association between Ramadan fasting and fetal growth indices, birth indices, cognitive scores, and long-term consequences. However, significant results were predominantly found in low-quality studies, and none of the high-quality studies reported a significant effect on these outcomes- Bilsen et al., 2021 (Er)
high fat diets
High fat diet during pregnancy has the potential to alter
a baby’s developing brain (Vogt et al., 2014) * Studies on mice
* mothers on a high-fat diet had pups with an altered hypothalamus, a part of the brain important for regulating metabolism
Rivera et al. (2015): This study investigated the impact of maternal obesity and a high-fat diet on offspring’s palatable food intake and dopamine signaling. It found that maternal high-fat consumption primed the offspring’s reward pathways, making them more prone to consume energy-dense foods later in life
Sullivan et al. (2010): This research focused on nonhuman primates and found that a chronic high-fat diet during pregnancy altered food preferences, highlighting the role of maternal diet in priming reward pathways
Kleinridders et al. (2016): This study demonstrated that maternal high-fat diet consumption resulted in hypothalamic inflammation in offspring, which disrupted energy balance regulation, increasing the risk of metabolic disorders such as obesity
stress
o’connor et al., 2018- (er)
This research highlights the significant impact of antenatal stress and anxiety on both obstetric outcomes and later child development. Severe stress during early pregnancy is linked to congenital abnormalities (e.g., cleft palate), while stress later in pregnancy is associated with preterm birth, low birth weight, and neurodevelopmental issues.
The findings suggest that:
Preterm birth & low birth weight – Increased risk due to maternal stress, leading to long-term health and behavioral problems.
Behavioral & emotional issues – Anxiety in late pregnancy predicts hyperactivity and emotional difficulties in children, independent of postnatal stress.
Neurological development – High maternal anxiety is linked to atypical laterality (mixed handedness), which is associated with neurodevelopmental conditions like dyslexia and autism.
HPA axis involvement – Maternal stress hormones (cortisol) may directly affect fetal development, altering blood flow and increasing risks of growth restriction and pre-eclampsia.
The timing of stress exposure plays a crucial role—early pregnancy stress impacts physical development, while later stress affects brain and emotional development. These findings underscore the importance of prenatal mental health care for both maternal and child well-being. Would you like more details on a specific aspect?
kim et al., 2016- Research has also explored the relationship between prenatal stress and the development of psychiatric disorders. Maternal stress during pregnancy can lead to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in offspring, increasing susceptibility to mental illnesses such as depression, schizophrenia, anxiety, and autism. These outcomes are thought to result from epigenetic modifications affecting gene expression related to stress response and neural development
feotal development and heart disease
oetal development and adult heart disease
* 16,000 individuals born in Hertfordshire from 1911-1930. * Compared mortality rates from coronary heart disease
(CHD) with birth data. * Size at birth related to CHD in adulthood. * Lower weight = increased chance
* Linear association; 7lb baby less risk than 6lb baby. * Growth restriction rather than prematurity. * Results confirmed in India, Europe, USA. * Range of other diseases also identified.
See Skogen & Overland (2012).
= undernourishment can speed up heart maturation to prepare for early birth- causing less muscle cells in the heart
behavioural outcomes (er)
research indicates that maternal diet during pregnancy can significantly influence the behavioral outcomes of offspring. For instance, a study by Chatzi et al. (2023) found that adherence to a healthy prenatal dietary pattern was associated with lower odds of autism diagnosis and improved social behaviors in children.
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Similarly, research by Ghazi et al. (2023) demonstrated that a high-quality diet characterized by fish and vegetable consumption during pregnancy was associated with reduced anxiety and hyperactivity problems in offspring, particularly in girls
critical analysis-
dutch study- While the study suggests that in utero famine exposure increases the risk of diseases in adulthood, postnatal conditions were not fully controlled. Many individuals who experienced famine in the womb also endured malnutrition, poor socioeconomic conditions, and stress after birth, which could contribute to the observed health outcomes.
Socioeconomic status, access to healthcare, and diet after birth could play a larger role than prenatal exposure alone.
STRESS AND BHEVAIOUR- Postnatal environment is also crucial: Children born to stressed mothers often grow up in stressful or unstable environments. It is difficult to determine whether prenatal stress alone or a combination of prenatal and postnatal stress is responsible for increased susceptibility to psychiatric disorders.
Genetic predisposition: Parents who experience high stress during pregnancy may also have genetic risk factors for psychiatric disorders, which they pass on to their children. This makes it hard to separate nature (genes) from nurture (prenatal environment).
