Biological changes throughout pregnancy Gestamosurrogacy

Biological changes throughout pregnancy

Since the early stages of pregnancy, the pregnant woman’s body undergoes a series of visible changes, some of which are only detectable through clinical examinations. These changes are necessary for the body to adapt and function according to the baby’s needs. It's important to remember that these changes, while significant, are temporary and will revert once the pregnancy ends, offering hope and patience to expectant mothers.

Circulatory System

During pregnancy, the abdomen and several other areas expand, and blood volume increases to support the uterus, placenta, skin, kidneys, and breasts, raising cardiac output. The heart rate may increase by 12–20 beats per minute to ensure fetal survival. Uterine growth and organ shifts can slightly tilt the heart, affecting blood return and potentially causing edema, varicose veins, and clots. It's important to note that these changes are temporary and will revert once the pregnancy ends, offering hope and patience to expectant mothers. Iron and hemoglobin levels drop due to the absence of menstruation, normalizing by the second trimester, often causing dizziness, nausea, and weakness.

Respiratory system

The nasopharyngeal capillaries dilate, the airways narrow, and the Eustachian tubes become obstructed, so congestion and slight changes in voice tone are common. The thoracic diameter increases slightly, and the functionality of the diaphragm and lungs is limited due to the growing uterus. The increasing levels of progesterone tell the brain that the pregnant woman should take more and deeper breaths, which causes her to exhale more carbon dioxide to avoid accumulation and could increase feelings of fatigue, choking, or risk of hyperventilation.

Metabolism

During pregnancy, hormones like estrogen, progesterone, HCG, cortisol, and prolactin increase, leading to higher vaginal secretions, breast milk production, and a constant state of hyper metabolism. Elevated diabetogenic hormones can raise blood sugar, promote fat storage, cause insulin resistance, and increase cholesterol and triglycerides. Metabolism in pregnancy changes to assimilate hormonal changes and promote metabolic balance in the baby, so the diet must be high in protein, vitamins and minerals, calcium, healthy fats, and carbohydrates.

Digestive system

Increasing levels of HCG, estrogens, and progesterone play a significant role in the changes in the digestive system during pregnancy. These changes might increase salivation, nausea, vomiting, relaxation of the digestive tract, slow digestive contractions, constipation, and the appearance of hemorrhoids. In addition, the lower esophageal sphincter (junction of the esophagus with the stomach) relaxes and dilates, and the stomach repositions (rises), favoring reflux, heartburn, and the appearance of ulcers. Pregnancy may also trigger intense food cravings, occasional pica disorder, and an increased risk of gallstones.

Renal-Urinary System

Due to the secretion of aldosterone, a hormone that regulates salt and water balance, and cortisol, a stress hormone, during pregnancy, the kidneys increase in size, and sodium retention and urine accumulation (renal hydronephrosis). The bladder, being under pressure from the constantly enlarged uterus, can fill more quickly with urine, which causes pregnant women to experience an increase in the frequency and urgency of urination during the day.

Immune system

The immune system plays a crucial role during pregnancy, adapting to the baby as a new organism and protecting it without attacking it. This is achieved by recognizing the baby as benign and not harmful. There may be peaks of lymphocyte depletion and vulnerability to acquiring viral or infectious conditions during gestation. The cells responsible for the immune tolerance mechanism are migrating toward the baby's immune system and must modify the uterine microbiota for their development. The endometrium may become inflamed at different stages of pregnancy, causing dynamic and variable lymphocyte responses between the pregnant woman and the baby.

Skin

Hormonal peaks may promote the appearance of spots or freckles (melasma), rashes, and pink or deep purple stretch marks due to the skin's stretching. The gums could swell or bleed, and acne and sensory alterations might appear. In addition, the neck or body folds darken due to increased melanin (or insulin resistance), the linea Alba appears on the abdomen, and nipples darken. The nails may become weak, and the joints and ligaments of the pelvic bones soften to promote the baby's adaptation and uterine growth.

Endocrine changes

When pregnancy begins, the hypothalami-pituitary axis is activated, increasing the secretion and release of hormones such as corticotropin (CRH) and Human Gonadotropin-Releasing hormone (GnRH). The size of lactotropic cells in the anterior pituitary and prolactin production increase, causing the breasts to enlarge and become sensitive to touch or friction. There is a significant rise in blood cortisol levels, leading to physical and psychological changes such as weight gain, acne, and difficulty staying focused or alert. Additionally, the placenta becomes an endocrine organ, producing adrenocorticotropic hormone (ACTH) and CRH and increasing the production of thyroid hormones like thyroid-stimulating hormone (TSH).

Bibliography

https://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0026-17422021000100039

https://www.reproduccionasistida.org/embarazo-y-cambios-fisiologicos/

https://www.msdmanuals.com/es-co/hogar/salud-femenina/embarazo-normal/cambios-f%C3%ADsicos-durante