SingaporeMotherhood | Pregnancy

September 2024

How is Heat affecting your Pregnancy? Is it Dangerous?

By June Wan

It’s official: temperatures are rising, and with them, health threats and general discomfort all around for us. If you are pregnant though, hotter weather can be even more harmful as the risk of heat-related illnesses is higher, says Dr Harvard Lin, Consultant Obstetrician, Gynaecologist and Urogynaecologist at the Asian Obstetrics & Gynaecology Centre (AOGC). This is because most women experience an increase in body temperature during pregnancy, making them more sensitive to high temperatures and thus, at higher risk of heat-related illnesses. We find out more from Dr Lin, and learn what pregnant women can do to stay cool as the mercury rises.

(See also: Best Prenatal & Postnatal Massage Services in Singapore)

Why are pregnant women more heat-sensitive?

Most women experience an increase in body temperature during pregnancy and this makes them more sensitive to high temperatures,¹ and at higher risk of heat-related illnesses. This increased sensitivity to heat is due to several physiological changes that occur during pregnancy:

1. Pregnancy boosts the metabolic rate as the body works harder to support a growing foetus. By week eight of pregnancy, your heart is already pumping blood 20 per cent faster than usual.² This increased metabolic activity generates more heat, making you feel warmer.
2. Your blood volume increases significantly during pregnancy to supply nutrients and oxygen to the foetus. Blood volume can increase by up to 50 per cent by week 34 of pregnancy.² This increase leads to more blood flowing closer to the skin’s surface, enhancing the sensation of warmth.
3. Hormones also play a part in making you feel warmer. Elevated levels of progesterone, which can cause the blood vessels to dilate, increases blood flow to the skin and raises body temperature.² This also causes blood pressure to drop, resulting in postural giddiness and even fainting spells.
4. Pregnancy weight gain can also contribute to you feeling hotter, as the body has to work harder to move and support the extra weight.

Interestingly, increased sweat production, which is the body’s natural response to help the body cool down, can cause the pregnant woman to feel warmer, especially in humid climates where sweat evaporates less efficiently.

Why is the pregnant body at higher risk of heat-related illnesses?

This is due to changes in your body’s capacity to regulate temperature when you are pregnant. These changes include:³

• Increased body mass and body fat which reduces your ability to dissipate heat to the environment.
• Decreased ratio of surface area to body mass that can make sweating less effective.
• Additional energy produced from the baby that increases your core body temperature.
• Your body needs to work harder to cool you and your developing foetus down.

(See also: Hospital Maternity Packages: Giving Birth in Singapore? Find the Best Maternity Packages here)

What are some of the complications that could develop due to increased heat?

Warmer weather can make pregnant women develop complications that can affect both their health and the health of the unborn baby. These include:⁴

1. Dehydration — Hot and humid weather causes the body to lose fluids and salts more quickly through sweat, leading to dehydration. Dehydration can lead to nutrient deficiencies. While mild dehydration is not typically dangerous as long as fluids are replenished quickly, severe dehydration can be dangerous.⁵
2. Fatigue — Extreme exhaustion or lack of energy is normal in pregnancy; but hot weather can further intensify this feeling.⁴
3. Heat exhaustion — During pregnancy, the body works harder to cool you and your developing baby, making you more susceptible to heat exhaustion.⁴
4. Heat stroke — Prolonged heat exhaustion can lead to heat stroke, which is the most severe type of heat-related illness. Heat stroke is dangerous for both you and your unborn foetus. It may lead to brain, heart, kidney and muscle damage.^6,7

Is it dangerous if a foetus is continuously exposed to high heat?

Yes. Continuous exposure to high heat during pregnancy can have adverse effects on the developing foetus, potentially leading to conditions and complications such as:

1. Neural tube defects — Elevated maternal body temperature, especially during the first trimester can increase the risk of neural tube defects such as spina bifida and anencephaly.^8,9
2. Congenital heart defects — High temperatures may also increase the risk of congenital heart defects, where the structure and function of the heart are abnormal.¹⁰
3. Preterm birth — Persistent high heat exposure is associated with an increased risk of preterm birth. Obviously, this can lead to a range of complications, including respiratory issues, developmental delays, and other long-term health problems.¹¹
4. Stillbirth — Severe heat exposure has been linked to an increased risk of stillbirth, where the foetus dies in the womb after 20 weeks of pregnancy.¹¹
5. Placental insufficiency — Heat stress can affect placental function, reducing the supply of oxygen and nutrients to the foetus.¹²
6. Low birth weight — Continuous exposure to high heat can result in low birth weight.¹²

What are some of the symptoms that a pregnant woman who is exposed to heat-related illnesses may feel?

Feeling warmer is part and parcel of a pregnancy, but you need to be extra careful when going out during hot days and partaking in strenuous activities, such as vigorous exercises, especially in hotter, more humid climates like ours.² If you have palpitations, breathlessness or night sweats, you might have a cardiovascular compromise.

(See also: 10 Prenatal Pilates Classes in Singapore for Pregnancy Fitness and Conditioning)

When should you see a doctor?

Consult a doctor as soon as these symptoms appear: a fever higher than 38.3°C, nausea, flu symptoms, fatigue and generally feeling unwell, muscle aches, and diarrhoea.

8 Ways to beat the heat and stay cool during pregnancy:

Beating the heat is easier than you think. Just be mindful of your surroundings and listen to what your body is telling you.¹

1. Rest or take a nap when you can in a cool, darkened room.
2. Invest in a cooling leg gel and take regular breaks to sit with your feet up in front of a fan or in an air-conditioned room.
3. Place a bowl of ice cubes in front of an electric fan for a cooling breeze.
4. Have a spray bottle filled with water to cool your face and body.
5. Place a wet towel on your head or neck, or fill a bowl with cold water to put your feet in.
6. A lukewarm shower or bath can help during the day. At night it can be soothing and may help you get a more restful night’s sleep.
7. If you have another child, sitting with your feet in the water of a shaded paddling pool is a good way to cool down, as well as keeping watch while your child enjoys the water.
8. Avoid going out in the hottest part of the day, usually mid to late afternoon. Limit trips or shopping when temperatures are at their highest.

(See also: Top 12 Foods to Eat for the Best Nutrition during Pregnancy)

Featured image: wayhomestudio on Freepik

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