All these recommendations about macro and micronutrients are great but very difficult to follow. So what concequences could happen if a pregnant woman underfed or overfed herself and her unborn child ?
But much more important, what could happen if a pregnant woman does not care about what she puts into her mouth ? In addition to an inappropriate nourishment, cigarettes, alcohol, and even caffeine are a concern during gestational and lactation periods.
The unborn child’s response to undernutrition is a catabolic consumption of substrates (molecule upon which an enzyme acts to create an environment) to provide energy. If prolonged, the fetus changes its metabolic rate and alters the production of hormones and the tissues’ sensitivity to the hormones. Also, the fetus prepares to store nutrients as fat in anticipation of poor postnatal nutrition. The decreased requirement for substrates and the lowering of metabolic rate slows down the development and leads to a lower and less than ideal weight at birth.
Furthermore, the consequences of undernutrition on the unborn support the thrifty phenotype hypothesis which states that the fetal intra-uterine environment has repercussions on the susceptibility to chronic diseases later in life. Indeed, the fetal adaptations permanently alter insulin and glucose metabolism (problems could occur if a malnourished fetus is born into an adequate or overfed environment).
To support this hypothesis a study done in the 90’s, following 64 years old men, showed that extremely bad glucose tolerance was observed in low birth weight men who became obese later in life.
On the other hand, maternal obesity can affect both mother and child. For women, the risks include heart diseases, type two diabetes and hypertension (in short most common obesity related diseases), and children have a greater risk of future obesity, heart diseases and also type two diabetes.
Also, when a pregnant woman has diabetes, a history of gestational diabetes (during a previous pregnancy), a family history of diabetes, glycosuria (excretion of glucose unfiltered by the kidney into the urine) or obesity, these factors, in addition to increasing the risks of diabetes for the child, can damage fetal growth (birth defects, stillbirth, prematurity, macrosomia, neonatal hypoglicemia…). However, it can be prevented by a well-balanced diet between macronutrients and micronutrients, exercise and a close follow-up testing.
Beside inadequate or excessive weight gain during pregnancy, tobacco is also a risk factors at the onset. You have probably heard from medical prevention campaigns that women must stop smoking in the perspective procreation, but why ?
Evidence indicates that exposure to tobacco smoke during pregnancy adversely affects children’s respiratory health by decreasing lung growth and increasing the risk of respiratory infections, and symptoms, including long-term effect on children’s respiratory health. Maternal smoking during pregnancy exposes the fetus to carcinogens and other toxins in tobacco that are metabolized into more potent active compounds, which are even stronger precursors of wheezing and asthma than postnatal environmental tobacco smoke. Several studies showed that 5% to 15% of asthma children cases could be prevented through the elimination of exposure to maternal smoking.
Furthermore, these findings suggest that nicotine or other substances released by maternal smoking can predispose the fetal brain which is in a critical period of its development to subsequent addictive influence of nicotine consumed more than a decade later in life. Nicotine like other addictive drugs, can alter gene expression and can produce long-lasting functional and structural changes in dopaminergic neurons (neurotransmitters involved in motor control and precursor of the adrenalina and noradrenalina), an effect that might be particularly profound in the developing brain.
Smoking was associated with dose-dependant increases in the risk of very or moderately preterm delivery. A change from being unexposed to being exposed was shown, in a cohort of women with a first delivery at term, to lead to a higher risk of a preterm delivery in the second pregnancy. A change from smoking to not smoking on the other hand, reduces the risk of a subsequent preterm delivery.
The occurrence of complications connected with smoking is probably correlated with the amount of cigarettes smoked per day. But smoking remains a high risk factor during pregnancy and predominately on the unborn for whom the chances to own a healthy body are altered.
Preterm delivery could also be associated with alcohol consumption. A study showed than over seven or more alcoholic drinks (whatever type of alcohol) per week could slightly increase the risk of preterm delivery. But there are no safe amounts, types or times that are acceptable for the consumption of alcohol during pregnancy.
As a matter of fact, the possibility of direct toxic effects of alcohol on fetal development is a well founded hypothesis.A study showed that prenatal alcohol exposure could lead to fetal alcohol syndrome which can result in hyperactivity, cognitive deficits and increased risks of other psychiatric disorders in the fetus. Genetic risks of ADHD (attention deficit / hyperactivity disorder) may be overlooked if environmental variables (alcohol and other addictive substances) that mark interacting factors are not measured. The same study provides evidence that a genetic variation of DAT1 (membrane-spanning protein implicated in deficit hyperactivity disorder) is involved in higher-order interactional effects that might include direct effect of maternal alcohol consumption.
Less suspicious but not less dangerous, caffeine is another daily substance that pregnant women should restrain or even withdraw from their diet. Since caffeine is readily absorbed through the digestive tract, it freely crosses the placenta and may directly interfere with fetal development. Moreover, in comparison with menstruated women, caffeine is metabolized more slowly during pregnancy.
Mothers who drink coffee have twice the risk of giving birth to a low birth weight child than those who do not drink any coffee. The association between caffeine and the intra-uterine growth retardation increases with the amount ingested, with double the risk for moderate consumers (150mg – 300mg of caffeine per day) and almost four times the risk for heavy consumers (more than 300mg of caffeine per day). Moreover, if the same heavy consumers maintain their consumption, they have a higher risk of preterm delivery than women who reduce their intake. Even a dose of 200mg of caffeine significantly decreases blood flow in placental villi. To give you an idea of caffeine consumption, there are 75mg of caffeine in an expresso and 145mg of caffeine in a coffee. Therefore, one coffee or two expressos per day are the upper safe limit for a pregnant woman who wants a pregnancy and a delivery without complication.
Finally, another study showed that the ingestion of caffeine may increase the risk of an early misscarriage among non-smoking women carrying fetuses with normal karyotypes (simple picture of a person’s chromosomes).
In order to avoid any risk, along with alcohol and smoking, caffeine consumption must be reduced or even stopped.
To conclude these admonitories and maximize the chances for a successful conception, one should :
- eat balanced high quality products in sane proportions
- eat small and frequent meals (snacks)
- drink water for two
- avoid fasting and skipping meals
- avoid smoking and smoky environments
- stop drinking alcohol
- reduce or even cease caffeine consumption (green tea being a great alternative to coffee)
If one respects the previous guidlines and asks for a physician’s advice, who can assess one’s health, one can hope for a smooth and healthy gestational and postnatal experience.
Naturally, a healthy body is not obtained by staying still. Moving and training is significant and even essential for pregnant women and recent mothers. So, stay tuned for the next article on training and modified exercises for pregnant women.
1. William’s basic nutrition and diet therapy, by Staci Nix, 14th Edition, 2013
2. Effects of Maternal Smoking during Pregnancy and Environmental Tobacco Smoke on Asthma and Wheezing in Children, by F.D. Gilliland, Y-F Li, J.M. Peters, 2001
3. Influence of smoking on smoking, by Klejewski A., Urbaniak T., Pisarska-Krawczyk M., Sobczyk K., 2012
4. Maternal smoking during pregnancy and smoking by adolescent daughters, by D. B. Kandel PhD, P. Wu, PhD, M. Davies, MPH, 09.1994
5. The influence of gestational age and smoking habits on the risk of subséquent preterm deliveries, S. Cnattingius, M.D., PhD, F. Granath, PhD, G. Peterson, BSc, B.L. Harlow, PhD, 23.09.1999
6. Maternal nutrition during pregnancy and health of the offspring, by M.S. Martin-Gronert and S.E. Ozanne, 2006
7. Alcohol consumption during pregnancy and the risk of preterm delivery, by K. Albertsen, A-M Nybo Andersen, J. Olsen, M. Gronbaek, 07.2003
8. A Common Haplotype of the Dopamine Transporter Gene Associated With Attention-Deficit/Hyperactivity Disorder and Interacting With Maternal Use of Alcohol During Pregnancy, by Keeley-Joanne Brookes, BSc; Jon Mill, PhD; Camilla Guindalini, BSc; Sarah Curran, MRCPsych, PhD; Xiaohui Xu, MD; Jo Knight, PhD; Chih-Ken Chen, MD, PhD; Yu-Shu Huang, MD; Vaheshta Sethna, BSc; Eric Taylor, FRCP, FRCPsych, PhD; Wai Chen, MRCPsych; Gerome Breen, PhD; Philip Asherson, MRCPsych, PhD, 2006