Prenatal nutrition
Prenatal nutrition addresses nutrient recommendations before and during pregnancy. Nutrition and
Prenatal nutrition has a strong influence on birth weight and further development of the infant. A study at the National Institution of Health found that babies born from an obese mother have a higher probability to fail tests of fine motor skills which is the movement of small muscles such as the hands and fingers.[1]
A common saying that a woman "is eating for two" while pregnant implies that a mother should consume twice as much during pregnancy, but is misleading. Although maternal consumption will directly affect both herself and the growing fetus, overeating excessively will compromise the baby's health as the infant will have to work extra hard to become healthy in the future. Compared with the infant, the mother possesses the least biological risk. Therefore, excessive calories, rather than going to the infant, often get stored as fat in the mother.[2] On the other hand, insufficient consumption will result in lower birth weight.
Maintaining a healthy weight during
Background
Barker's hypothesis – influences of birth weight on health in later life
The "Barker Hypothesis", or
When this theory was first proposed, it was not well accepted and was met with much skepticism.[6] The main criticism was that confounding variables such as environmental factors could attribute to many of the chronic diseases such that low birth weight alone should not be dictated as an independent risk factor.[5] Subsequent research studies supporting the theory attempted to adjust these environmental factors and in turn, provided more convincing results with minimal confounding variables.[5]
"Barker's Hypothesis" is also known as "
If the mother has an inadequate diet then it signals the baby that the living condition in the long term will be impoverished.[5] Consequently, the baby adapts by changing its body size and metabolism to prepare for harsh conditions of food shortages after birth.[5] Physiological and metabolic processes in the body undergo long-term changes as a result of restricted growth.[5] When the living environment switches from the condition of malnutrition to a society of abundant supply of nutrients, this exposes the baby to a bountiful environment that goes against what its body is designed for and this places the baby at a higher risk of adult diseases later in adulthood.[5] By the same token, if the fetus growing in the womb of a healthy mother is exposed to prolonged famine after birth, the infant would be less adaptive to the harsh environment than low-birth-weight babies.[4]
Pedersen's hypothesis – influences of maternal glucose concentration on fetal growth
In 1952, the Danish physician Jørgen Pedersen of the University of Copenhagen, formulated the hypothesis that maternal hyperglycemia during pregnancy might cause fetal hyperglycemia, thus exposing the fetus to elevated insulin levels. This would result in an increased risk of fetal macrosomia and neonatal hypoglycemia.[7]
The
Subsequently, alterations of Pedersen's Hypothesis took place:
Historical cases
Various nutritional conditions, both times of
The Dutch famine
Since small birth weight is associated with an increased risk of chronic diseases in later life, and poor maternal nutrition during gestation contributes to restricted fetal development, maternal malnutrition may be a cause of increased disease susceptibility in adulthood.
The
The Dutch Famine during World War II had a profound effect on the health condition of the general public, especially women who conceived during the period of time. The period of maternal starvation is shown to have limited intrauterine growth and has been identified as one of the most important contributors to
The French paradox
The
One explanation suggested for the paradox is the potential impact of nutritional enhancements during pregnancy and the first months and years of life that would positively influence the health of following generations: After the defeat in the
Recommendations for pregnant women
Gestation stages
Germinal stage is the stage from fertilization to about 2 weeks.
Embryonic stage is approximately from 2 weeks to 8 weeks. It is also in this stage where the blastocyst develops into an embryo, where all major features of humans are present and operational by the end of this stage.
Fetal stage is from 9 weeks to term. During this period of time, the embryo develops rapidly and becomes a fetus. Pregnancy becomes visible at this stage.
-
Embryo at 8 weeks after fertilization[17]
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Fetus at 18 weeks after fertilization[18]
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Fetus at 38 weeks after fertilization[19]
Pre-pregnancy weight and gestational weight gain
The pattern and amount of weight gain is closely associated with gestational stages. Additional energy is required during pregnancy due to the expansion of maternal tissues and stored to support fetal development.
In the
In the
Generally, a normal weight is strongly recommended for mothers when entering gestation, as it promotes overall health of infants.
Since the total weight gain depends on pre-pregnant body weight, it is recommended that underweight women should undergo a larger weight gain for healthy pregnancy outcomes, and overweight or obese women should undergo a smaller weight gain.[3]
Normal weight women
Women having a BMI of 18.5~24.9 are classified as having a normal or healthy body weight. This group has the lowest risk of adverse birth outcomes.[3] Their babies are least likely to either be low-birth weight or high-birth weight. It is advised that women with a normal weight before pregnancy should gain a total of 11.5 kilograms to 16.0 kilograms throughout gestation, which is approximately 0.4 kilogram per week in the second and third trimesters.[3]
In order to maintain a steady weight gain, the mother should engage in mild physical activities. Participating in aerobic activities such as walking and swimming 3 to 4 times a week is usually adequate.[3] Vigorous physical activity is not recommended since an excessive loss of calories is induced which is not sufficient to support fetal development.
A proper diet is also essential to healthy weight gain. The common saying "a woman is eating for two" often leads to mothers thinking that they should eat twice as much. In reality, only a small increase in caloric intake is needed to provide for the fetus; approximately 350 calories more in the second trimester and 450 calories more in the third trimester.
Underweight women
Women are classified as underweight if they have a pre-pregnant BMI of 18.5 or below.[3] Low pre-pregnancy BMI increases the risk of low birth weight infants, but the risk can be balanced by an appropriate gestational weight gain from 12.5 to 18.0 kilograms in total, or about 0.5 kilogram each week in the second and third trimesters.[3]
Underweight women usually have inadequate nutrient stores that are not enough to provide for both herself and the fetus.[3] While exercise and a proper diet are both needed to maintain the recommended weight gain, a balance between the two is very important. As such, underweight mothers should seek individualized advice tailored especially for themselves.[3]
Overweight and obese women
Women with a high pre-pregnancy weight are classified as overweight or obese, defined as having a BMI of 25 or above.[3] Women with BMI between 25 and 29.9 are in the overweight category and should gain between 7.0 and 11.5 kilograms in total, corresponding to approximately 0.28 kilogram each week during the second and third trimesters.[3] Whereas women with BMI of 30 or above are in the obese category and should gain only between 5.0 and 9.0 kilograms overall, which equates to roughly 0.2 kilogram per week in the second and third trimesters.[3]
Diet, exercise or a combination of both has been seen to reduce weight gain in pregnancy by 20% and reduce high blood pressure.[21] Diet with exercise may reduce the risk of caesarean section, having a large baby and having a baby with serious breathing problems.[21] Diet and exercise help pregnant women not gain too much weight during pregnancy when compared with giving the women no help to control weight gain or routine care (usually one session in the pregnancy).[21]
In general, walking is encouraged for mothers classified in this category.[3] Unfortunately, estimated energy requirements for them are not available.[3] As such, they are encouraged to record activity and intake level. This can be done with the help of tools such as My Food Guide Servings Tracker from Health Canada and EATracker that are available online.[3] In extreme cases where the BMI exceeds 35, help from a registered dietitian is recommended.[3]
Summary table
The following table summarizes the recommended rate of weight gain and total weight gain according to pre-pregnancy BMI for singleton pregnancies. The first column categorizes the type of body weight based on the Body Mass Index. The second column summarizes the total recommended weight gain for each type of body weight, and the third column presents the corresponding weekly weight gain during the period when the fetus undergoes rapid growth (during second and third trimesters). In extreme cases, the amount of total and weekly weight gain can vary by a factor of two depending on a woman's pre-pregnant weight. For example, a woman in the obese category is recommended to gain a total of 5~9 kilograms, whereas an underweight woman needs to gain up to 18 kilograms in weight.
Pre-pregnancy BMI Category | Recommendated Total Weight Gain | Weekly Weight Gain
(after 12 weeks) |
Underweight
BMI <18.5 |
12.5~18 kg (28~40 lb) | 0.5 kg (1.0 lb) |
Healthy weight
BMI 18.5~ 24.9 |
11.5~16 kg (25~35 lb) | 0.4 kg (1.0 lb) |
Overweight
BMI 25.0~ 29.9 |
7.0~ 11.5 kg (15~25 lb) | 0.3 kg (0.6 lb) |
Obese
BMI ≥ 30 |
5.0~9.0 kg (11~20 lb) | 0.2 kg (0.5 lb) |
.[22]
Recommendations for low and high birth weight
Diagnosis
To have a good estimate of birth weight,
Crown-rump length can be used as the best ultrasonographic measurement for correct diagnosis of gestational age during the first trimester.[23] This correlation between crown-rump length and gestational age would be most effectively shown when no growth defects are observed in the first trimester.[23] If growth defects were observed in the first trimester, then the measurement of the date of last menstrual period becomes quite important since the crown-heel length has become less of a reliable indicator of gestational age.[23]
After the 20th week of pregnancy, the mother would need to visit the doctor for the measurement of fundal height, which is the length from the top portion of the uterus to the pubic bone.[24] The length measured in centimeters should correspond to the number of weeks that the mother has been pregnant.[24] If the measured number is higher or lower than 2 centimeters, further tests using ultrasound would be needed to check the results.[24] Another way to estimate fetal size is to look at the mother's weight gain.[24] How much weight the mother gains can be used to indicate fetal size.[24]
Low birth weight
There are two ways to determine
Many factors, including maternal, placental, and fetal factors, contribute to the cause of impaired fetal growth.[23] There are several maternal factors, which include age, nutritional status, alcohol use, smoking, and medical conditions.[23] Insufficient uteroplacental perfusion is an example of a placental factor.[23] Chromosomal abnormalities and genetic diseases are examples of fetal factors.[23]
Complications for the infant include limitations in body growth since the number and size of cells in tissues is smaller.[24] The infant likely did not receive enough oxygen during pregnancy so the oxygen level is low.[24] It is also more difficult to maintain body temperature since there is less blood flow within the small body.[24]
As such, it is necessary to monitor oxygen level to make sure that it doesn't go too low. If the baby can't suck well, then it may be necessary for tube-feed.[24] Since the baby cannot maintain body temperature sufficiently, a temperature-controlled bed would help to keep their bodies from losing heat.[24] There are ways to help prevent SGA babies. Monitoring fetal growth can help identify the problem during pregnancy well before birth.[24] It would be beneficial to seek professional help and counseling.
High birth weight
Research shows that when birth weights of infants are greater than the 90th percentile of the growth chart for babies of the same gestational age, they are considered large for gestational age or LGA.[26] This indicates that these babies are weighing more than 90% of babies of the same gestational age.[26]
Many factors account for LGA babies, including
There might be a need for early delivery if the baby gets too big and perhaps Caesarean section would be needed.[26] Since the baby is bigger, there's a higher chance of injury when coming out of the mother's body.[26] To increase the blood glucose level in blood, a glucose/water solution can be offered to the infant.[26]
There are ways to help prevent LGA babies. It is necessary to monitor fetal growth and perform pregnancy examinations to determine health status and detect any possibility of unrecognized diabetes.[26] For diabetic mothers, careful management of diabetes during pregnancy period would be helpful in terms of lowering some of the risks of LGA.[26]
Points to consider
The goal of pregnancy is to have a healthy baby. Maintaining healthy and steady weight gain during pregnancy promotes overall health and reduces the incidence of prenatal
Since conditions during pregnancy will have long-term effects on adult health, "moderation" should be considered for both dietary and physical activity recommendations. Most importantly, the total recommended pregnancy weight gain depends on pre-pregnant body weight, and weight issues should be addressed before pregnancy.
Research
Malnutrition and the placenta
The placenta may adapt to maternal malnutrition in an effort to support fetal development and protect against adverse nutritional exposures. In pregnant mice, undernutrition and high fat diets have been shown to alter both placental size and structure, including the expression of key transport systems.[28] Placentae from mothers fed a high fat diet appeared to adapt to excessive nutrient supply, while placentae from undernourished mothers were less mature with impaired transport.[28] These placental adaptations could help to explain why offspring from malnourished pregnancies experience altered growth.[28]
Future direction for research
It is reasonable to expect higher weight gain for multiple gestations.[3] Recommendations for women carrying twins are given but more research should be done to precisely determine the total weight gain, as these ranges are wide.[3] Also, the ranges for underweight women carrying twins is unknown. There was not enough information to recommend weight gain cutoffs and guidelines for women carrying three or more babies, women of short stature (<157 centimetres), and pregnant teens.[3] Estimated energy requirements (EER) for overweight/obese women are unavailable so more research is needed to evaluate on that.[3] There are also important links between nutrition and mental health across pregnancy. For example, a woman experiencing low mood may be more likely to smoke, use alcohol or neglect her diet[29]
Practical advice for mothers
The following general tips can be helpful to pregnant women. It would be beneficial to maintain adequate physical activity to meet energy needs from the food consumed.
If the fetus is predicted to have low birth weight, in addition to the general recommendations, it would be ideal to increase caloric intake, which can be done by having extra Food Guide Servings daily.[30] If the fetus is predicted to have high birth weight, smaller and more frequent meals should be consumed to allow better weight management.[33] Moderate sugar intake, such as fruit juices, is also suggested.[33] It is essential to limit food and beverages with high calories and salt content.[30]
See also
- Smoking and pregnancy
- Nutrition and pregnancy
- Fetal Origins Hypothesis
- Fetal Programming
References
- ^ "Parent obesity linked to delays in child development, NIH study suggest". National Institutes of Health. 3 January 2017. Retrieved 27 January 2017.
- ^ De Leon, Victoria. "Weight Problems During Pregnancy and the Effect on Your Baby". Losing Pregnancy Weight. Archived from the original on 4 March 2011. Retrieved 3 March 2011.
- ^ a b c d e f g h i j k l m n o p q r s t u v w "Draft Prenatal Nutrition Guidelines for Health Professionals – Maternal Weight and Weight Gain in Pregnancy". Health Canada. 2009. Archived from the original on 29 November 2010. Retrieved 1 December 2010.
- ^ PMID 11689495.
- ^ S2CID 28124828.
- ^ PMID 11127263.
- ^ Erhöhte Blutzuckerwerte bei Schwangeren gefährden das Kind
- ^ The influence of maternal glucose metabolism on fetal growth, development and morbidity in 917 singleton pregnancies in nondiabetic women
- ^ Maternal Glucose Concentration Influences Fetal Growth, Gestation, and Pregnancy Complications
- PMID 3402161.
- ^ Maternal Glycemia and Neonatal Adiposity: New Insights from the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study
- ^ PMID 16876341.
- ^ ISBN 978-3-8055-7780-9.
- ^ BBC News: Health French health mystery
- ^ Size Matters: How Height Affects the Health, Happiness, and Success of Boys
- ^ "germinal stage". Mosby's Medical Dictionary, 8th edition. Elsevier. Retrieved 2 January 2020.
- ^ 3D Pregnancy Archived 27 September 2007 at the Wayback Machine (Image from gestational age of 10 weeks). Retrieved 13 December 2010. A rotatable 3D version of this photo is available here Archived 16 September 2007 at the Wayback Machine, and a sketch is available here Archived 27 September 2007 at the Wayback Machine.
- ^ 3D Pregnancy Archived 27 September 2007 at the Wayback Machine (Image from gestational age of 20 weeks). Retrieved 13 December 2010. A rotatable 3D version of this photo is available here Archived 16 September 2007 at the Wayback Machine, and a sketch is available here Archived 27 September 2007 at the Wayback Machine.
- ^ 3D Pregnancy Archived 27 September 2007 at the Wayback Machine (Image from gestational age of 40 weeks). Retrieved 13 December 2010. A rotatable 3D version of this photo is available here Archived 16 September 2007 at the Wayback Machine, and a sketch is available here Archived 27 September 2007 at the Wayback Machine.
- ^ "Canadian Guidelines for Body Weight Classification in Adults". Health Canada. 2003. Archived from the original on 25 March 2010. Retrieved 27 November 2010.
- ^ PMID 26068707.
- ^ "Weight Gain During Pregnancy: Reexamining the Guidelines". Institute of Medicine. 2009. Archived from the original on 23 October 2009. Retrieved 28 November 2010.
- ^ PMID 12777538.
- ^ a b c d e f g h i j k l "Small for Gestational Age", Lucile Packard Children's Hospital, 2010. Retrieved 9 November 2010.
- PMID 12730476.
- ^ a b c d e f g h i j k l Children's Hospital of Wisconsin, "Large for Gestational Age", Children's Hospital and Health System, 2010. Retrieved 9 November 2010.
- ^ BabyCenter Medical Advisory Board, "Labor complication: Big baby (macrosomia)", BabyCenter, L.L.C., 2006. Retrieved 5 November 2010.
- ^ S2CID 210997335.
- ^ a b c d "Prenatal Nutrition Guidelines for Health Professionals – Background on Canada's Food Guide", Health Canada, 2009. Retrieved 23 November 2010.
- ^ Larissa Hirsch, "Staying Healthy During Pregnancy", The Nemours Foundation, 2008. Retrieved 17 November 2010.
- ^ Ministry of Health Promotion, "The Juicy Story on Drinks", Queen's Printer for Ontario, 2010. Retrieved 18 November 2010.
- ^ a b Alberta clinical experts, "Prediabetes or Impaired Glucose Intolerance" Archived 2 February 2010 at the Wayback Machine, HealthLink Alberta, 2008. Retrieved 21 November 2010.