How Does Your Body Change During Pregnancy?

A woman’s body undergoes remarkable changes during nine months of pregnancy. Some changes are visible such as skin changes, while others are not. Pregnancy hormones are responsible for various body changes in pregnancy. They cause anatomical and physiological changes to a woman’s body to accommodate, nourish, and deliver the baby.

Although some medications are prescribed to ease some discomfort, several body changes are physiological and resolve without interventions after childbirth. Read this post to know about various body changes during pregnancy.

Body Changes During Pregnancy

1. Hormonal changes

Pregnancy hormones can make your body and mind feel all over the place right now. You may blame the hormones for emotional changes (mood swings) such as crying fits or rages in pregnancy. Hormonal functions affect your mood, metabolism, growth, development, relax the ligaments, delivery, breastfeeding, etc.

Pregnancy hormones include (1):

• The human chorionic gonadotropin hormone (hCG) is a key pregnancy hormone made in the placenta, preparing the body for implantation and gestation. This hormone produces nausea in the first trimester and stimulates the production of progesterone hormone from the corpus luteum.

• The human placental lactogen (hPL) hormone, also known as human chorionic somatomammotropin, is made by the placenta. This hormone modifies the maternal metabolic state to provide energy to the fetus. They may also stimulate milk glands in the breasts. Estrogen hormone is usually formed from the ovaries and placenta during pregnancy and helps to support the pregnancy.

• Progesterone hormone is produced by the ovaries and placenta and helps the implantation of the fetus. It also loosens the joints to help the body accommodate the growing uterus and prepare for birth.

• Oxytocin eases labor pain, helps cervical opening, and controls bleeding after birth. Milk production and mother and baby bonding is also regulated by oxytocin.
  

• Prolactin hormone helps in bonding and milk production.

• The relaxin hormone loosens and softens the ligaments to widen the pelvic area and cervix for labor.

• Prostaglandins hormones help the cervix to prepare for labor.

The RAAS (renin-angiotensin-aldosterone) system that regulates the blood pressure and fluid and electrolyte balance in the body can be stimulated in early pregnancy. This may increase renin, angiotensin II (ANG II), and aldosterone hormones in the blood, causing sodium and water retention. This hormonal activation helps expand total plasma volume by holding excess fluid in the body (2). The thyroid gland is also affected, and the parathyroids increase in size slightly, covering the increased requirements for calcium.

2. Sensory changes

The following sensory changes are common during pregnancy:

• Smell Many women experience a heightened sense of smell (olfaction) during pregnancy. Although anecdotal evidence suggests hyperosmia (increase in olfactory sensitivity) in pregnancy, there is no conclusive scientific evidence. Small concentrations of an odor can be sensed due to increased sensitivity. Gonadal hormones such as estrogen and progesterone are likely to cause smell changes in pregnancy (3).

• Taste Pregnancy hormones can alter your sense of taste (dysgeusia). This is why most pregnant women may show aversion to some foods they craved before pregnancy. Sometimes pregnant women may experience a metallic taste or sour taste in their mouth even though they are not eating anything.

Some prenatal vitamins can also cause a metal mouth, so changing vitamins may reduce this taste. You may also try citrus juices or foods and brushing teeth, and rinsing your mouth with baking soda or mild salt solution. You may feel normal olfaction soon after delivery (4).

• Vision Physiologic changes, pregnancy-specific eye diseases, and changes in pre-existing eye disease can contribute to ocular changes during pregnancy. The following types of eye changes and diseases are common in pregnancy (5):

• Corneal changes may occur due to physiological reasons such as water retention. Corneal sensitivity, thickness, and curvature can be changed due to water retention in the body. These corneal changes can alter refraction and affect vision. Eyeglasses are recommended to correct these refractory changes since contact lenses may cause intolerance in some women. Refractive surgeries are also contraindicated since this may change after delivery.

• Dry-eye syndrome can be seen in early pregnancy in many women due to disruption of lacrimal cells. This may improve during the third trimester and postpartum.

• IOP (intraocular pressure) variations are often seen in the second half of pregnancy. IOP can affect healthy eyes due to physiological changes such as generalized acidosis, decreased episcleral venous pressure, decreased scleral rigidity, and increased aqueous outflow. IOP returns to normal levels within two months postpartum.

• Adnexal (outside eyeball) changes of eyelids and conjunctiva can be due to hyperpigmentation such as chloasma. Some may experience ptosis (drooping eyelid) during pregnancy due to fluid or hormonal changes. These adnexal changes usually resolve after delivery.

• Pregnancy-specific eye diseases such as retinal vascular changes may occur in cases of preeclampsia and eclampsia. Some can have retinal detachment (exudative or serous type) with these conditions. The risk for vision problems is seven times greater in women with eclampsia and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count)

3. Breast changes

Breast changes begin from early pregnancy in most women. Pregnancy hormones cause these changes to prepare your body for breastfeeding. As a result, the breast can be swollen and tender during pregnancy. You may also notice small bumps in the areola (the area around the nipples). Breasts continue to change throughout the pregnancy, and they increase in size and feel full in later months (6). By the third trimester, colostrum, a yellow, watery pre-milk, may appear on the nipples, and nipples may stick out more.

4. Cervical changes

Cervix keeps the fetus until the term in the uterus. Cervical dilation and effacement allow fetal delivery and close within minutes after delivery; gradually, the opening narrows within a few weeks. Pregnancy hormones remodel the cervix to stay closed during pregnancy and dilate during childbirth (7). The cervix will also become thick and form a mucus plug. At the end of pregnancy, the cervix softens gradually, and the mucus plug is lost near the delivery time.

5. Nail and hair changes

Texture and growth of nails and hair may change in pregnancy. Some may experience faster and stronger hair and nail growth, while some women can have increased hair fall and nail slits during pregnancy. Changes in hormones can be a reason, and some may experience postpartum hair fall. However, the hair and nails return to normal over time (8).

6. Skin changes

Skin changes are normal and common during pregnancy, resulting from hormonal changes. Although many skin changes in pregnancy can cause anxiety by affecting how you look, most are harmless and subside after delivery.

Common skin changes in pregnancy include (8) (9):

• Stretch marks usually appear in the second half of pregnancy, on the belly when the skin stretches to accommodate the growing baby. Pregnant women may also notice stretch marks on breasts since they enlarge. Stretch marks can also appear on the hips and buttocks in pregnancy and even in other parts of the body, depending on weight gain. These marks may gradually fade off after delivery, and maintaining a healthy weight in pregnancy may help minimize stretch marks.

• The “mask of pregnancy” is the hyperpigmentation of the skin with darker patches (dark spots), known as chloasma or melasma. These patches can be yellowish or brownish and usually appear over cheeks, nose, and around eyes.

• Linea nigra, also known as the pregnancy line, is the dark line on the middle of the lower abdomen. This is also caused by hyperpigmentation due to hormonal changes.

• Moles (melanocytic naevi) may become larger and darker in some women during the pregnancy. These are observed in the moles on the abdomen and breasts due to skin stretching and often resolve after pregnancy. Most mole changes during pregnancy are benign (non-cancerous) and symmetrical. If you are concerned about asymmetrical or atypical changes, you should visit a dermatologist (10).

• Freckles (ephelides) are dark patches or tan marks of color or pigmentation under the skin. These may also become darker and larger during pregnancy.

• Visible veins such as spider veins on the skin appear due to increased blood volume and blood vessels changes in Varicose veins that are swollen and blue become visible due to diminished blood flow in the legs since the uterus compresses veins draining to the heart from the lower parts of the body.

Pregnancy-related skin diseases may include (9):

• Pruritic urticarial papules and plaques of pregnancy (PUPPP) are small hives and red bumps starting from the abdomen. These skin lesions can spread to breasts, thighs, and buttocks and appear as large patches. They can be itchy, and doctors may recommend anti-itch creams or steroid creams to control them.

• Phlemingoid gestationis is a rare pregnancy-related skin condition in the second or third trimester or immediately after delivery. This condition causes blisters on the skin, especially on the abdomen. Doctors may recommend anti-itch creams and oatmeal in bath water to manage phlemingoid gestationis.

• Prurigo of pregnancy is tiny, itchy bumps on the skin that often last for several months. This may occur anywhere on the skin and anytime during It can be treated with medications.

Cholestasis of pregnancy (obstetric cholestasis) can cause itchy skin in the palms and soles due to bile salts accumulation. This may often occur in the third trimester and subsides after delivery. Some pre-existing skin conditions can also improve or worsen during pregnancy. Doctors may prescribe anti-itch creams and moisturizers to ease skin discomforts in pregnancy (9).

7. Circulatory system changes

The cardiovascular system undergoes significant physiological changes in pregnancy. These changes are necessary to ensure adequate uteroplacental circulation for optimal growth and development of the fetus.

The following hemodynamic changes are seen in pregnancy (11):

• Vasodilation (widening of blood vessels) of the maternal kidneys and systemic vasculature is seen as early as five weeks after complete development of the uteroplacental circulation.

• Peripheral vascular resistance decreases in the first and middle of the second trimester and increases in later weeks. There can be around 35% to 40% decrease in vascular resistance during pregnancy, and it returns to non-pregnant levels within two weeks postpartum.

• Cardiac output increases throughout the This is observed on echocardiography or cardiac magnetic resonance imaging (MRI) since invasive measures are not used in pregnancy. A sharp rise is seen in the first trimester and continues to increase in the second trimester, and there can be a 45% increase in cardiac output by 24 weeks in singleton pregnancy. Nearly 15% higher cardiac output is observed in twin pregnancies.

• Arterial blood pressure decreases during pregnancy, including the systolic and diastolic pressure (SBP and DBP), central SBP, and mean arterial pressure. There can be a 5 to 10mmHg drop in blood pressure during the second trimester, and the arterial pressure then increases in the third trimester and returns to preconception values. Hypertensive disorders such as gestational hypertension and preeclampsia may change these measurements.

• Heart rate increases throughout the pregnancy by 10 to 20 beats per minute (bpm) and reaches maximum rate in the third trimester. There can be around a 20 to 25% increase in heart rate in pregnant women.

Healthy pregnant women can also experience shortness of breath during activities and fatigue due to increased resting cardiac output. Low levels of exercise can induce maximum cardiac output in pregnancy, so that you may plan prenatal exercises accordingly as per the doctor’s recommendations.

Relaxation of blood vessels due to pregnancy hormones can lower blood pressure (hypotension) and result in dizziness and fainting (syncope). Fainting occurs when less blood is pumped to the brain, and it is not dangerous to the baby. Sitting down or lying down on the left side is recommended to avoid falling and hurting yourself when you feel dizzy during pregnancy (12).

8. Respiratory changes

Biochemical and mechanical changes can alter the pulmonary function, gas exchange, and ventilatory pattern during pregnancy. The following respiratory changes are observed in pregnancy (13):

Biochemical changes: Hormonal changes can cause ventilatory changes in pregnant women, including:

• Progesterone triggers the respiratory center by increasing sensitivity to carbon dioxide. Progesterone hormone also affects the smooth muscle tone in the airways leading to a bronchodilator effect and nasal congestion.

• Estrogen can increase the number and sensitivity of progesterone receptors in the respiratory areas of the brain.

• Prostaglandins F2a that stimulate uterine smooth muscles during labor can constrict bronchial smooth muscles and increase airway resistance. However, prostaglandins E1 and E2 may cause bronchodilator effects.

Mechanical changes: Expanding the uterus can cause chest wall pressure and lung volume changes since it compresses and elevates the diaphragm. These changes include:

• Changes in thoracic pressure lead to reduced functional residual capacity (FRC) (volume of air in the lungs after passive exhalation) and expiratory reserve volume (ERV) (volume of air exalted during forceful breath out) of the lungs. However, an increase in inspiratory capacity helps maintain a stable ventilation rate.

• Increased oxygen consumption and FRC reduction in pregnancy can lower the oxygen reserve of the mother. Compliance of the lungs (ability to expand) and diffusing capacity (rate of gas exchange) remains unchanged. This can be due to the counter effects of hormones.

Respiratory function is not different in single and multiple pregnancies.  Mechanical changes are more evident from the second half of pregnancy when the uterus expands.

9. Metabolic rate changes

Basal metabolic rate (BMR) changes during pregnancy. Some studies show that an increase in BMR is associated with body weight and pre-pregnancy total body fat (TBF) in 14 weeks of gestation. These measurements could cause a 40% change in metabolic rate.

In 32 weeks of gestation, body weight, TBF, fat-free mass (FFM), insulin-like growth factor (IGF-1), circulatory changes, and thyroid hormones can also affect the metabolic rate. There can be 60% changes in metabolic rate in later pregnancy. Pre-pregnancy nutritional situations are also considered while assessing pregnancy energy requirements and metabolic rate (14).

10. Body temperature changes

Some women may experience a rise in body temperature during pregnancy. Although there is limited evidence on core body temperature changes in pregnancy, many women say they feel hotter than usual. This can be more evident in warmer weather. However, hot weather can increase the risk for fatigue, dehydration, heat exhaustion, fainting, and heatstroke in pregnancy. So, ensure to stay cool during pregnancy (15).

An episode of hyperthermia or fever (increased body temperature) in pregnancy can affect fetal development, especially during the early weeks. This may also increase the risk of functional and structural defects, miscarriage, and prenatal death. However, these effects may depend on the degree of elevated temperature, duration, and gestational age (16).

You may stay well hydrated to avoid dehydration. Cool baths, cool water sprays, keeping wrists in cold running water, pouring water, etc., can reduce the risk of hyperthermia in pregnancy. You may also treat fevers with medications. Try to do exercises in indoor spaces early or late hours when the environment is less hot to avoid heat stroke during workouts.

Pregnancy-related body changes usually resolve after childbirth over time. You may seek medical care for any concerning discomforts since some conditions can be at ease with medications or other treatments. Ask your doctor to know the safe and effective prenatal exercises, skin and hair products, and other medical treatments.

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