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Pregnancy is a period that brings significant changes to a woman’s body. The growth of the fetus is strongly influenced by the mother’s lifestyle habits, and routines that may seem harmless in daily life can sometimes lead to unexpected risks. In particular, smoking, drinking alcohol, sleep deprivation, and poor eating habits have been medically identified as factors that increase the risk of miscarriage, premature birth, and fetal growth restriction. Furthermore, for pregnant women planning to undergo NIPT (non-invasive prenatal testing), which has gained attention in recent years, reviewing lifestyle habits is also an important part of preparation. This article will provide a detailed explanation of dangerous lifestyle habits to avoid during pregnancy, the risks behind them, and concrete approaches for improvement.
1. The Effects of Smoking on the Fetus
1-1. The Dangers of Passive Smoking
Smoking is one of the habits that should be most strongly avoided during pregnancy. Cigarette smoke contains harmful substances such as nicotine and carbon monoxide, which can pass through the placenta and adversely affect the fetus. Carbon monoxide in particular interferes with oxygen supply in the blood, leading to fetal hypoxia, growth restriction, and increased risk of premature birth. Moreover, even if the pregnant woman herself does not smoke, passive smoking at home or in the workplace presents the same risks.
1-2. The Relationship Between Smoking and NIPT
NIPT is a test that examines the risk of chromosomal abnormalities in the fetus using maternal blood. Smoking can alter blood components, which may affect the efficiency of blood collection and testing. Although it does not directly impair test accuracy, from the perspective of health management, quitting smoking is considered essential.
2. Alcohol Consumption and Fetal Alcohol Syndrome
2-1. Even Small Amounts Carry Risk
Drinking alcohol during pregnancy is often misunderstood as “safe in small amounts,” but the only way to completely eliminate the risk of fetal alcohol syndrome (FAS) is abstinence. Alcohol passes through the placenta to the fetus and may interfere with the development of the central nervous system, heart, and other organs. Particularly in early pregnancy, when organ formation is underway, even small amounts of alcohol can raise concerns.
2-2. Alcohol and Emotional Impact
Drinking during pregnancy has also been linked to developmental and learning disabilities after birth, and it may worsen maternal anxiety or tendencies toward dependence. Strict abstinence from alcohol is required to ensure a safe and secure pregnancy.
3. Excessive Caffeine Intake
3-1. The Effects of Caffeine on the Fetus
Caffeine, found in coffee, tea, and energy drinks, stimulates the central nervous system. During pregnancy, caffeine metabolism slows, and the fetus has little to no ability to break it down. Excessive intake has been pointed out as a factor that may increase the risk of low birth weight or miscarriage.
3-2. Guidelines for Safe Intake
The World Health Organization (WHO) and the European Food Safety Authority (EFSA) recommend that pregnant women keep daily caffeine intake below 200 mg. Since one cup of coffee contains about 100 mg, the guideline is within two cups per day.
4.Excessive Dieting and Nutritional Deficiency
4-1. Misconceptions and Risks Regarding Weight Management During Pregnancy
Weight gain during pregnancy is unavoidable, but some women severely restrict food intake due to reasons such as “weight gain makes childbirth harder” or “I don’t want to look overweight.” However, weight gain in pregnancy is necessary for fetal growth and does not simply mean “getting fat.” The Ministry of Health, Labour and Welfare’s “Dietary Guidelines for Pregnant and Lactating Women” sets appropriate weight gain ranges according to pre-pregnancy BMI:
BMI below 18.5 (underweight): 9–12 kg
BMI 18.5–25 (normal): 7–12 kg
BMI 25 or higher (overweight): to be discussed individually with a physician
Keeping weight gain far below these levels is said to increase the risk of low birth weight or premature birth.
4-2. The Effects of Extreme Dieting on the Fetus
Severe dietary restrictions may cause the following:
・Growth restriction: Insufficient nutrients can cause intrauterine growth restriction (IUGR).
・Low birth weight: Babies weighing less than 2,500 g may have weak immunity and strength, with increased risk of lifestyle-related diseases later in life.
・Delayed neurodevelopment: Nutritional deficiencies in early to mid-pregnancy increase risks such as neural tube defects.
・Reduced amniotic fluid: Maternal undernutrition may reduce amniotic fluid, affecting fetal development and safety during delivery.
In other words, the mother’s desire to “lose weight” may burden the fetus with lifelong health risks.
4-3. Essential Nutrients During Pregnancy and Their Roles
Pregnancy requires more nutrients than usual. It is important to understand those that are particularly likely to be deficient and aim for a balanced diet.
・Folic acid: Essential in early pregnancy. Prevents neural tube defects and supports brain and spinal cord development. Recommended daily intake is 400 μg, often supplemented with tablets.
・Iron: Maternal blood volume increases to about 1.5 times by late pregnancy, raising the risk of iron-deficiency anemia, which can cause premature birth or low birth weight.
・Calcium: Essential for fetal bone and tooth development. Deficiency increases risks of reduced maternal bone density or gestational hypertension.
・Protein: Required for muscle, organ, and placenta formation. Should be consumed in balance from meat, fish, eggs, and soy products.
・DHA/EPA: Essential fatty acids important for fetal brain and vision development. Should be supplemented through oily fish or tablets.
・Vitamin D: Supports calcium absorption. Often deficient due to lack of sun exposure or dietary restrictions.
A Japanese-style diet combining staple food, main dish, and side dishes is considered ideal to avoid deficiencies or excess.
4-4. Pitfalls of Trendy Diets
Some women attempt diets such as “low-carb” or “fasting” during pregnancy. However, carbohydrates are the fetus’s main energy source for brain development, and drastic reduction is dangerous. Fasting may cause hypoglycemia, leading to dizziness or fainting in the mother and growth restriction in the fetus. Commercial “diet foods for pregnant women” and supplements may also contain unverified ingredients. It is important not to impose restrictions on one’s own judgment but to consult a physician or nutritionist.
4-5. Relationship with NIPT
NIPT involves blood collection, and if the mother is severely malnourished, blood condition may be unstable, increasing the likelihood of anemia during collection. Poor nutritional status may also hinder recovery after testing. Thus, proper nutrition management is especially important for pregnant women undergoing NIPT.
4-6. Practical Methods for Healthy Weight Management
The ideal is balancing “not gaining too much” and “not being too thin.” Practical methods include:
・Frequent small meals: Instead of three large meals, divide into four or five smaller ones to reduce digestive burden while ensuring adequate nutrition.
・Smart snacks: Incorporate nuts, yogurt, and fruit to prevent hunger and supplement nutrients.
・Japanese-style meals: Base meals on rice, fish, and vegetables, while limiting fried foods and sweet breads.
・Consult professionals: If weight gain exceeds guidelines, consult a doctor instead of deciding alone.
Weight management during pregnancy is about “adjustment,” not “restriction.” A healthy lifestyle should be pursued with fetal development as the top priority.
5. Sleep Deprivation and Excessive Stress
5-1. Risks of Sleep Deprivation
Pregnant women often experience shallow sleep due to hormonal influences or discomfort from body changes. Chronic sleep deprivation, however, lowers maternal immunity, increases risk of hypertensive disorders, and may negatively affect fetal development.
5-2. Stress and Fetal Development
Studies have shown that strong stress in pregnant women can lead to premature birth or fetal growth restriction. Stress hormones may also pass through the placenta and affect fetal development, even influencing behavioral development after birth.
6. Habits That Increase the Risk of Infection
6-1. Consumption of Raw or Undercooked Food
Toxoplasma and Listeria bacteria may be transmitted through raw meat or unpasteurized cheese. These can cause serious congenital conditions in the fetus, so thorough cooking is essential.
6-2. Contact with Pets
Toxoplasma can also be transmitted through cat feces. It is recommended that pregnant women avoid cleaning litter boxes or use gloves when doing so.
7. Support for Quitting Alcohol, Tobacco, and Drug Dependence
7-1. Utilizing Smoking and Alcohol Cessation Clinics
If quitting is too difficult, it is effective to use smoking cessation or alcohol cessation programs at medical institutions. Since willpower alone may not be enough during pregnancy, professional support is recommended.
7-2.Understanding and Support from Those Around You
When family and partners join in efforts to quit smoking and drinking, the burden on pregnant women is greatly reduced. Improving lifestyle habits is not just a personal matter but an opportunity to raise the health awareness of the entire family.
Conclusion
Dangerous lifestyle habits to avoid during pregnancy include smoking, drinking alcohol, excessive caffeine intake, extreme dieting, sleep deprivation, and behaviors that increase infection risk. All of these are directly linked to the health of both mother and fetus, and each improvement contributes to a safer pregnancy. Maintaining healthy lifestyle habits is also an important preparation for undergoing prenatal tests such as NIPT. By reviewing lifestyle habits and receiving medical support when necessary, pregnant women can ensure a healthy and secure pregnancy for both mother and child.
