Stress during pregnancy can affect the baby?
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Says Michel Odent, the renowned French obstetrician, that the main concern of those around them or care for a pregnant woman should be to ensure their emotional wellbeing.
And is that, with advancing knowledge of physiology of pregnancy, also increases the certainty that the mother's emotional state is crucial for the development of fetal infant and even for future health.
Over recent years, several studies have been pointing out that severe stress during pregnancy, for example by a high pressure at work, abuse in relationships, life events like death of a close family member, or even rejection of an unwanted pregnancy may have a major impact, as we will.
Does this mean that mothers are responsible to suffer stress and transmission to their babies? No way. The most common is that pregnant women can not do anything to change their situation or experiences that suffers. Should a woman feel guilty for being fired while pregnant (if it is even possible that the cause of dismissal is the pregnancy itself)? Should accuse itself to suffer for the death of a beloved family?
Of course not. At best, we may be aware, before pregnancy, the importance of well-being. Perhaps some women can improve our way of life to enjoy peace of mind during pregnancy. Many do not have that luck. Therefore, it is rather the society as a whole that should become aware of the need to protect and ensure the emotional well-being of pregnant women. For them and their children.
Preterm birth and low birth weight
One consequence of severe maternal stress that have been brought more insistent during the last decade is the increased incidence of preterm birth and low birth weight. The studies on this subject are so numerous that there have been several review articles summarizing the accumulated knowledge to date. In general, the hypothesis that handle the researchers is that high levels of stress hormones associated with depression and anxiety, such as cortisol, can reduce blood supply to the placenta and induce premature labor.
A new study to be published in the August 2009 issue of American Journal of Public Health shows that hard work or a work day more than 32 hours per week in the first trimester of pregnancy is associated with low birthweight birth and increased risk of giving birth to a baby small for gestational age. The study was conducted in Amsterdam (Netherlands), using a completed questionnaire to 8266 women, about their working conditions.
Although it is common for pregnant women to reduce or interrupt their working day at the end of gestation, the results of this study suggest that reducing working hours in the early months of pregnancy may be beneficial for women with stressful jobs full time.
Prenatal stress and fetal death
Moreover, recently in Denmark studied the impact of psychological stress on the risk of stillbirth. Researchers have collected data of 19 282 pregnancy with one baby, and maternal stress have been measured at 30 weeks of gestation using a standard questionnaire on mental health.
Fetal death (after 28 weeks of gestation) occurred in 66 pregnancies (0.34% of all pregnancies). Women with high stress levels had a 80% increased risk compared with women with intermediate levels of stress. That is, if it occurred in 0.34% of total pregnancies in the case of women with high stress levels occurred in 0.61%. As can be seen, the incidence remains very small and should not be a source of anxiety for pregnant mothers suffering from stress and suffering for it, but it is significant: something happens to stress during pregnancy, and should not be minimize their potential impact.
The study took into account the possible influence of factors such as maternal age, number of children, the BMI of the mother before pregnancy, consumption of snuff, alcohol, coffee, marital status, and level of education without none of these factors altered the results. Neither changed the results by excluding women with pregnancy complications (diabetes, hypertension, vaginal bleeding).
This is the first study that has examined the effects of prenatal stress on the risk of fetal death, and indicates that high levels of stress are associated with nearly twice the risk of stillbirth. The authors believe that stress, depression and anxiety are associated with high levels of stress hormones such as catecholamines. In animal studies, has been that elevated levels of catecholamines coincide with a reduction of blood flow to the placenta and fetal asphyxia. Although some habits, such as snuff consumption may increase the risk of fetal death, and are more common in women who are experiencing stress, the researchers were careful to control this variable, without any evidence that would affect study results.
Neurodevelopmental
Gene deregulation, destruction of brain cells and synapses (connections between neurons), inhibition of dendritic development, improper development of the corpus callosum and cerebellum are some of the mechanisms by which maternal stress affects the fetal neurological development. Exposure to high levels of prenatal stress, especially during the first weeks of pregnancy can adversely affect fetal brain development, determining alterations in the development of intellectual and language skills in children.
In 2004, in effect, a group of Canadian researchers published the results of a study initiated in 1998, following an ice storm in Quebec. This natural disaster exposed a large number of pregnant women to a high stress, and the researchers could track such pregnancies and the subsequent development of children up to 2 years of age. This found that the more severe was the level of prenatal stress, the lower the development of intellectual and language skills of children at 2 years, especially if stress exposure had occurred in the early stages of pregnancy.
More recently, in March 2007 a team from the Institute of Reproductive and Developmental Biology, Imperial College London (8) (9) published a review of a set of studies are showing that if a mother is stressed during pregnancy, more likely that your baby is emotional or cognitive problems (such as risk of attention deficit hyperactivity disorder, anxiety, and delayed language development), irrespective of the effects of maternal postnatal depression or anxiety. The researchers acknowledged not knowing yet what forms of maternal stress or anxiety are the most harmful, but suggested that the relationship with your spouse can be important in this regard. They also pointed out that the extent of these effects is clinically significant because 15% of emotional or behavioral problems are due to prenatal stress or anxiety.
Axis activity hypothalamic-pituitary-adrenal (HPA axis, what is?) And the release of corticotropin-releasing hormone (CRH) is under the influence of stress, through blood cortisol levels. The fetal environment may be altered if stress alters maternal hormonal profile, and we know that there is a direct relationship between levels of maternal and fetal cortisol.
However, still not completely understood the mechanisms involved in this interaction. For example, maternal cortisol response to stress is reduced throughout gestation and during early pregnancy, the connection between maternal and fetal cortisol is not as strong. It is possible that the effects of maternal stress and anxiety in the development of the fetus and the baby might be mitigated by other factors such as nutrition during pregnancy. It has been suggested that a state of hypervigilance or anxiety, or intense activity of the HPA axis may be an adaptive response to environmental stress during development, but persists in the form of vulnerability to neurodevelopmental disorders.
Other research suggests that prenatal exposure to stress may increase the risk of autism (10). Apparently, there is evidence in both animals and humans that prenatal stress can cause abnormal behavior after the birth to coincide with the symptoms of autism, and other abnormalities that are present in autism, such as learning deficits, seizure disorders , perinatal complications, abnormal immune and neuroinflammatory and postnatal low tolerance to stress in children.
However, the overall risk of having a baby with these conditions is low. Even women who had suffered while pregnant life events as serious as the death of another son had a very low risk that her baby had such birth defects. The study, published in 2000 in the prestigious medical journal Lancet, congenital disorders affecting about 0.65% of all pregnancies, compared to 1.18% of pregnancies in women under extreme stress.
As the stress not only affects the nervous system but also the cardiovascular, hormonal and immune, there is good reason to suspect that severe emotional stress (especially during the first trimester of pregnancy when many organs are forming), could cause birth defects, explain Dorthe Hansen and his team.
The researchers examined the medical records of 3,500 women who had been exposed during pregnancy to situations of extreme stress, because their partners or other children had been diagnosed with cancer, had suffered a heart attack or had died. They then compared the number of babies born with birth defects with the number of births of a control group of 20,000 women who had been exposed to these events.
Babies born to women who had suffered serious experiences during the first trimester of pregnancy were more likely to have defects in neural crest cell structure that is believed to contribute to the development of the head and face, and palate, teeth , nose, parts of the eyes, ears, throat and even the skull. These are precisely the structures have been associated with more stressful events during pregnancy.
Women who had suffered the loss of another child during the first trimester of pregnancy were those who were more likely to have babies with these defects, up to five times more likely to cleft lip and heart defects, and if death of the eldest son was sudden, up to eight times more. In contrast, the probability was not as high if the event serious had happened before pregnancy or in the second or third trimester. There was no relationship between birth defects and experiences such as death or serious illness of a partner during pregnancy. Nor was he relationship between severe stress and other types of birth defects.
Behavioral changes: the hypothesis of fetal programming
More than 14,000 women in the British county of Avon, pregnant between 1991 and 1992, have participated to date, along with their children in the Avon Longitudinal Study of Parents and Children (ALSPAC), also known as "Children of the 90's." This follow-up study, the most important thing has been done so far by its magnitude, has confirmed the lasting effect that has anxiety during pregnancy on child development. According to the ALSPAC, children of mothers with anxiety at 32 weeks gestation showed severe behavioral problems during childhood, increasing by 60% the risk of severe problems. Prenatal maternal anxiety was associated with attention deficit hyperactivity at 4 years (which did not happen with the children of mothers who suffered postnatal depression) (12). At 6 and 7 years, children of mothers who had had anxiety in the third quarter continued to show more behavioral problems and emotional disturbances (13).
We also found that the effect of maternal anxiety is different at different times of pregnancy, for example, high levels of maternal anxiety at week 18 was associated with a higher percentage of left handedness or problems.
In another prospective study it was found that upon reaching adolescence, children of mothers who had suffered anxiety in the first half of pregnancy had higher impulsivity and lower IQ.
Why are these behavioral changes? Some researchers try to explain some of the effects of prenatal stress from the fetal programming hypothesis. It is a difficult concept to explain: not given by genetics, which is set before being conceived, nor by the habits of life during childhood, adolescence or adulthood. The fetal programming occurs in between these two periods, during our gestation in the womb.
The hypothesis of fetal programming or Barker hypothesis (the first researcher to point this item) (15) states that the structure and function of various organs and tissues are "programmed" or permanently altered in response to certain stimuli or attacks during critical periods of fetal development. Thus, for example, small size at birth or in childhood is associated with increased susceptibility to adverse effects in adulthood (cholesterol, diabetes, hypertension, etc.).
When the mother has to face major hazards (which produce severe stress), the baby is scheduled to be born into a world full of dangers. The state of hypervigilance, characterized by rapid changes in child care could be an adaptive response in an environment fraught with danger. In our culture, where great importance to the ability of concentration and attention, this hypervigilance is not necessary and is seen as a problem, not an advantage.