The Effects of Being Too Thin or Too Overweight During Pregnancy on the Baby【supervised by doctor】

Introduction

During pregnancy, some women may experience difficulty eating due to morning sickness, resulting in becoming too thin, while others may overeat due to cravings, leading to becoming overweight.

Does becoming too thin or too overweight during pregnancy have an impact on the baby?

Too Thin During Pregnancy

Guidelines for Being Too Thin

According to the “Dietary Guidelines for Pregnant and Lactating Women Starting Before Pregnancy” announced by the Ministry of Health, Labour and Welfare, pregnant women with a pre-pregnancy BMI of less than 18.5, indicating underweight, are advised to aim for a weight gain of 12 to 15 kilograms during pregnancy.

Furthermore, pregnant women with a BMI between 18.5 and less than 25.0, indicating normal weight, are advised to aim for a weight gain of 10 to 13 kilograms.

If the weight gain falls significantly below these guidelines, it may be considered as being too thin.

Effects of Being Too Thin on the Baby

Early Pregnancy

During the early stages of pregnancy, if the intake of food is insufficient and there is a lack of folic acid intake, the risk of neural tube defects in the fetus increases.

On the other hand, during this period, many pregnant women experience morning sickness, and even though they understand that being too thin is not good, they may have difficulty eating as they would like. If you cannot eat enough, it is advisable to make good use of supplements such as folic acid.

The Effects of Being Too Thin or Too Overweight During Pregnancy on the Baby【supervised by doctor】

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Mid-Pregnancy

By the time the mid-pregnancy period begins, the placenta is fully developed, allowing nutrients consumed by the mother to be delivered to the baby through the placenta. If the mother is malnourished during this period, the baby may not receive sufficient nutrients.

In such cases, the baby may become smaller compared to the gestational age due to low nutrition, leading to a condition called intrauterine growth restriction (IUGR).

Late Pregnancy

Pregnant women who are too thin are reported to be more prone to premature birth. If premature birth occurs in the late stages of pregnancy and the baby is born early, the insufficient development of organs may necessitate admission to the neonatal intensive care unit (NICU), and there is a possibility of lasting complications.

Just Before Birth

When pregnant women are too thin, they have a higher risk of anemia. If childbirth occurs while anemic, labor may weaken due to fatigue, and there is a possibility of decreased oxygen supply to the fetus. Additionally, in cases of excessive bleeding during delivery, the likelihood of requiring a blood transfusion increases, leading to elevated risks during childbirth.

Being Too Overweight During Pregnancy

Guidelines for Being Too Overweight

According to the “Dietary Guidelines for Pregnant and Lactating Women Starting Before Pregnancy” announced by the Ministry of Health, Labour and Welfare, pregnant women with a pre-pregnancy BMI of 25.0 to less than 30.0 are advised to aim for a weight gain of 7 to 10 kilograms. Additionally, for pregnant women with a pre-pregnancy BMI of 30 or higher, individualized care is necessary, with a maximum weight gain guideline of 5 kilograms.

If the weight gain significantly exceeds these guidelines, it may be considered as being overweight.

Effects of Being Too Overweight on the Baby

Early Pregnancy

During the early stages of pregnancy, various organs of the baby are formed, making it a crucial period. If the mother is obese during this time, there is said to be a higher risk of neural tube defects such as spina bifida, congenital heart defects, and umbilical hernia.

Furthermore, due to obesity, it may become more challenging to assess the condition of the fetus through ultrasound.

Mid-Pregnancy

If obesity is present, the risk of gestational diabetes increases.

When a mother develops high blood sugar due to gestational diabetes, there is an increased risk of conditions such as gestational hypertension, abnormal amniotic fluid levels, and shoulder dystocia.

Moreover, the baby in the womb may also develop high blood sugar, leading to risks such as miscarriage, structural abnormalities, macrosomia (large birth weight), cardiac hypertrophy, hypoglycemia, polycythemia, electrolyte abnormalities, jaundice, and fetal death.

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Late Pregnancy

If obesity is present, the risk of developing gestational hypertension syndrome increases.

Gestational hypertension syndrome, when severe, can lead to elevated blood pressure, proteinuria, as well as seizures (eclampsia), cerebral hemorrhage, dysfunction of the liver and kidneys, and a condition called HELLP syndrome, which involves hemolysis, elevated liver enzymes, and low platelet count.

Additionally, complications such as intrauterine growth restriction, placental abruption where the placenta detaches from the uterine wall causing decreased oxygen supply to the baby, fetal distress, and in some cases, fetal death, may occur due to poor fetal development.

Just Before Birth

Maternal obesity or gestational diabetes can promote excessive fetal growth, increasing the risk of macrosomia, where the baby weighs 4000 grams or more. Macrosomic babies can be a cause of complications during delivery such as shoulder dystocia, cephalopelvic disproportion, and uterine atony leading to postpartum hemorrhage. It’s also not uncommon for the delivery method to be a cesarean section.

Weight Management During Pregnancy

Revising Diet

During pregnancy, it is important to consume a balanced diet in appropriate amounts. The leaflet of the “Dietary Guidelines for Pregnant and Lactating Women Starting Before Pregnancy” announced by the Ministry of Health, Labour and Welfare lists the following dietary guidelines for pregnant and lactating women

• Focus on “staple foods” to ensure sufficient energy intake.
• Obtain ample vitamins and minerals from “side dishes” to address potential deficiencies.
• Combine “main dishes” to ensure adequate protein intake.
• Ensure sufficient calcium intake from dairy products, green and yellow vegetables, legumes, and small fish.

Source: Ministry of Health, Labour and Welfare – Dietary Guidelines for Pregnant and Lactating Women Starting Before Pregnancy

Is Dieting Okay?

During pregnancy, since the mother’s diet directly affects the baby’s nutrition, it’s important to avoid strict dieting or extreme food restrictions.

If excessive weight gain is a concern, it’s advisable to seek guidance from a healthcare provider and manage diet and exercise appropriately under their supervision.

Effects of Being Too Thin or Too Overweight During Conception

Being too thin or too overweight can also be a cause of infertility.

In the case of being too thin, the body prioritizes vital functions for survival, leading to a decrease in ovarian function and making ovulation less likely to occur. As a result, it becomes difficult to conceive.

On the other hand, it’s also known that overweight women may have difficulty getting pregnant. This is because being overweight can lead to abnormalities in glucose and lipid metabolism, making ovulation disorders more likely to occur.

Testing the Baby’s Condition with NIPT (Non-Invasive Prenatal Testing)

During pregnancy, it’s common for mothers to worry about whether their baby is developing healthily. The condition of the baby is influenced not only by environmental factors such as the mother’s weight, but also by the chromosomes they inherit.

Prenatal testing allows for the examination of chromosomal abnormalities in the baby during pregnancy. While amniocentesis and chorionic villus sampling (CVS) provide definitive results, they carry the risk of miscarriage or stillbirth as they involve sampling amniotic fluid or placental tissue.

On the other hand, NIPT is performed using the mother’s blood, eliminating the risk of miscarriage or stillbirth. Although it’s considered a screening test rather than a diagnostic one, NIPT boasts high sensitivity and specificity rates of 99.9%, making it highly accurate.

NIPT can be conducted as early as the confirmation of pregnancy through ultrasound, allowing for earlier testing compared to other prenatal diagnostic methods. If you’re eager to learn about your baby’s condition early on, considering NIPT may be beneficial.

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Conclusion

Being too thin or too overweight can affect the course of pregnancy and fertility. If you’re concerned about your weight management, it’s advisable to consult your primary healthcare provider during prenatal check-ups and follow their guidance.

For those who are successfully managing their weight, it’s important to continue maintaining a balanced diet by referring to guidelines such as the “Dietary Guidelines for Pregnant and Lactating Women Starting Before Pregnancy.” This will help ensure proper nutrition intake throughout pregnancy.

Furthermore, we introduced NIPT. If you’re interested in learning more about chromosomal abnormalities in your baby, why not consider NIPT?