Physiological changes during pregnancy

Human Chorionic Gonadotropin (hCG) is a hormone produced by the developing placenta. It maintains the corpus luteum for the first 6-7 weeks of pregnancy, preventing menstruation and embryonic loss. hCG also stimulates testosterone production in the fetal adrenal medulla, crucial for the development of external genitalia.

Early Pregnancy Factor (EPF), an immunosuppressant, appears in the bloodstream soon after conception, supporting trophoblast (placental) growth. β-human chorionic gonadotropin (β-hCG) becomes detectable and is used, along with ultrasound, to confirm pregnancy.

Gonadotropin-Releasing Hormone (GnRH) increases during pregnancy, particularly in the first 24 weeks. This surge stimulates the placenta to produce more hCG.

The primary pregnancy hormones are progesterone and estrogen. These hormones are initially released by the corpus luteum but later produced by the placenta.

Hormonal changes play a crucial role in maintaining pregnancy, supporting the growth of the placenta, and preparing the mother's body for childbirth. They influence various body systems, ensuring a healthy environment for the developing fetus.

The hormones that increase during pregnancy are: Progesterone, Estrogen, hCG, hPL, Relaxin, ACTH, TSH, Vasopressin, Prolactin, Thyroid hormones (TH), Renin, Erythropoietin, Vitamin D, PTH, and Glucocorticoids.

Progesterone during early pregnancy inhibits contractions, prevents embryonic loss, supports decidual cell development, nourishes the embryo, maintains the endometrium, inhibits FSH and prevents ovulation.

Progesterone in later pregnancy promotes breast development, increases gland size, relaxes smooth muscle, expands the uterus, increases blood vessel capacity, which can lead to varicose veins, slows down the GI tract leading to constipation, regulates glucose, modifies the effects of placental lactogen and cortisol, and controls glucose and lipid availability.

hPL interferes with maternal insulin levels to increase serum glucose, which increases maternal fat storage.

Relaxin increases the flexibility of tendons to allow for fetal growth and birth. It also relaxes the uterus for the growing fetus and dilates the pubic symphysis and cervix for the birth passage.

ACTH stimulates the adrenal cortex, leading to increased cortisol levels.

TSH stimulates the thyroid to release thyroid hormone, which increases glucose availability and growth.

Vasopressin affects the constriction of smooth muscle, including blood vessels, uterus, and mammary gland.

Prolactin inhibits ovulation, controls the movement of salt and water, and produces milk.

TH increases maternal basal metabolic rate, plays a vital role in glucose availability and growth.

Oestrogen, produced by the placenta, plays crucial roles throughout pregnancy, including: relaxing pelvic ligaments for expansion of the uterus, supporting the growth of fetal and maternal tissues, and increasing cortisol levels.

The placenta is the primary source of oestrogen during pregnancy. Initially, the corpus luteum contributes to oestrogen production, but the placenta takes over as the primary producer.

Oestrogen relaxes pelvic ligaments, allowing the uterus to expand significantly from 2-3mm to 9mm during pregnancy, accommodating the growing fetus.

Oestrogen supports the growth of both fetal and maternal tissues, including the expansion of the uterus, breasts, and external genitalia.

Oestrogen stimulates an increase in cortisol levels during pregnancy. Cortisol plays a critical role in supporting fetal development and maternal adaptation to pregnancy.

Hormonal changes during pregnancy are vital for maintaining a healthy pregnancy and delivering a healthy baby. These changes support the growth of the placenta, prepare the mother's body for childbirth, and ensure the developing fetus has a healthy environment.

Relaxin, produced by the corpus luteum and later the placenta, increases throughout pregnancy to prepare the body for birth. It relaxes ligaments and joints, softens the cervix, and facilitates the delivery process.

Placental lactogen, produced by the placenta, prepares the breasts for lactation, contributes to maternal growth, and alters glucose availability to support fetal development.

Many pregnant women experience changes in their food preferences. Savory foods are often the first preference (associated with protein needs), followed by sweet foods (energy boost and social connection). Salty foods are typically preferred later on (to maintain fluid balance).

Pica is a craving for non-food substances like coal, chalk, or dirt. It's sometimes linked to nutritional deficiencies, but the exact cause is unclear.

Pregnancy hormones like progesterone relax smooth muscle, leading to slower digestion. This can result in constipation and heartburn.

Heartburn is caused by the relaxation of the cardiac sphincter (muscle between esophagus and stomach), allowing stomach acid to reflux upwards.

Pregnancy hormones increase insulin resistance, making more glucose available for the growing fetus. This leads to increased fat deposition and weight gain.

Nutrients cross the placenta through a combination of transport systems. Amino acids are actively transported, while glucose uses facilitated diffusion.

Hyperemesis gravidarum is a severe form of morning sickness, characterized by persistent vomiting and dehydration. It can be debilitating and may require hospitalization.

The urinary tract, including the collecting system and ureters, dilates due to progesterone relaxation of smooth muscle. This is a normal adaption during pregnancy.

Progesterone is a key hormone during pregnancy. It plays a vital role in preparing the uterus for implantation, maintaining the pregnancy, and supporting the development of the fetus. Progesterone also helps to prepare the breasts for lactation.

Progesterone increases blood flow to the kidneys, leading to an increase in glomerular filtration rate. This means more waste products are filtered out of the blood. Progesterone also increases aldosterone production, leading to sodium and water retention. This helps to maintain blood volume during pregnancy.

Progesterone relaxes smooth muscles throughout the body, including those in the uterus and blood vessels. This can contribute to varicose veins and oedema. Progesterone also stimulates breast development and growth, preparing the mammary glands for breastfeeding.

Gestational Diabetes is a type of diabetes that develops during pregnancy. It usually develops in the second or third trimester. The body struggles to regulate blood sugar levels during pregnancy.

Gestational Hypothyroidism is a condition where the thyroid gland doesn't produce enough thyroid hormone during pregnancy. It is caused by decreased TSH levels and results in fatigue, mood changes, and other symptoms similar to normal pregnancy.

Obstetric Cholestasis is a liver disorder that develops during pregnancy. It involves itching, particularly in the palms of the hands and soles of the feet. It is caused by leakage of bile salts into the bloodstream.

Pregnancy-related conditions like Gestational Diabetes, Gestational Hypothyroidism, and Obstetric Cholestasis are specific to the pregnant state. They are not present before pregnancy and usually resolve after delivery.

During pregnancy, the kidneys produce more erythropoietin (EPO), a hormone that stimulates the production of red blood cells, which helps to increase the oxygen-carrying capacity of the blood to meet the baby's needs.

Pregnancy causes an increase in blood flow to the kidneys, enhancing their filtering capacity and leading to increased creatinine clearance, which helps to remove waste products from the mother's body.

To ensure adequate oxygen and nutrient delivery to the developing fetus, the body increases blood supply to the kidneys and skin, leading to a 'glow' in pregnant women.

To prevent excessive bleeding during childbirth, the blood clotting system is enhanced leading to a higher risk of blood clots (thrombosis) in pregnant women.

Pregnant women breathe deeper rather than faster to get more oxygen, increasing their tidal volume (amount of air breathed in and out) by 40%.

The growing uterus pushes on the lungs, but pregnant women compensate by taking deeper breaths, ensuring efficient gas exchange.

The muscle fibers in the upper part of the uterus spiral around, creating powerful contractions that push the baby out. The lower part of the uterus has circular fibers, providing a controlled opening for the baby to pass through.

The uterus expands significantly due to hypertrophy (cell growth) and hyperplasia (increased cell number) to accommodate the growing fetus.