Maternal Physiological Changes in Pregnancy

In pregnant woman there are many physiological changes during pregnancy, which are entirely normal, including changes in different trimesters and changes in different systems like cardiovascular, metabolic, renal, hematologic, and respiratory changes. The progesterone and estrogens levels rise continually during pregnancy, and they suppress the hypothalamic axis and therefore also the menstrual cycle.

Endocrine system (non-reproductive) changes:

1. Pituitary hormones The levels of FSH/LH falls due to high levels of estrogen and progesterone, the levels of ACTH and melanocyte stimulating hormone increases, The levels of prolactin also increases, oxytocin also increases and ADH levels are unchanged.
2. Thyroid and parathyroid gland The concentration of Thyroxin-binding globulin increases due to increased estrogen levels. Levels of T4 and T3 increase during first half of pregnancy and then normal ranges are slightly reduced during second and third trimester. After first trimester the production of TSH is stimulated. This rise in TSH indicate iodine deficiency or sub clinical hypothyroidism. During pregnancy women are relatively iodine-deficient, the World Health Organization (WHO) recommends an increased intake of iodine during pregnancy.

Adrenal gland and pancreas Levels of cortisol increases during pregnancy, which helps in lipogenesis and fat storage. There is increase in insulin response so blood sugar remain normal or low. After early stages of pregnancy due to increased production of cortisol, progesterone, prolactin, and human placental lactogen the peripheral insulin resistance increases. Gestational diabetes is thought to reflect a pronounced insulin resistance of this sort.

Cardiovascular system changes 5 Peripheral vasodilation is present. There is increase in cardiac output by 20% by week 8, and then further increased up to 40% at week 20-28. There is further increase of cardiac output during labour and immediately after delivery, then it returns to normal within an hour. The increased cardiac output increase the heart rate of 10-20 beats per minute.

Respiratory system changes 9 There is increase in tidal volume by 200ml, there is increase in vital capacity and decrease in residual volume and there is no significant alteration in respiratory rate. Increase in metabolic rate and oxygen consumption due to increased oxygen demand. 1.2e) Alimentary system changes During early pregnancy nausea and vomiting are common. Specific cravings and appetite are usually increased. Constipation is common in pregnancy due to reduced gastrointestinal motility and transit time. Which allows increased nutrient absorption.

Urinary tract changes the increased renal blood flow and glomerular filtration rate up to 50-60% is due to increased blood volume and cardiac output during pregnancy. Which reduce blood levels of urea, urate, bicarbonate, creatinine due to increased excretion. The bladder smooth muscle relaxes increasing capacity which leads to risk of urinary tract infection.

Hematological changes There is increase in plasma volume by 50% during pregnancy. Due to this Dilutional anemia occurs. By the end of second trimester the total red cell mass increased due to elevated erythropoietin levels. Pregnancy needs addition amounts of iron for about 1000mg.

Metabolic changes Increased basal metabolic rate by 15-20% over the course of pregnancy. There is no increase in energy requirements during first or second trimesters, in third trimester there is an increase by 200 kcal. For pregnant women with normal body mass index (BMI) the recommended weight gain in pregnancy is 11.4 to 15.9 kg. The weight gain is due to fetus, membranes, placenta and amniotic fluid the rest is maternal stores of fat and protein.

Diagnosis of Pregnancy

Woman herself can detect the beginning of pregnancy based on symptoms, or by using pregnancy tests. 18 and some non-pregnant women strongly believe that they are pregnant and also have some of the physical changes. This condition is referred as a false pregnancy.19 pregnancy can be diagnosed by physical changes, biomarkers, scanning.

Physical signs There are number of early symptoms that can signify pregnancy. Physical signs associated with pregnancy include:

• Basal body temperature increases for 2 weeks after ovulation.
• The menstrual periods are stopped
• Hegar’s sign – uterus isthmus become soften
• Goodell’s sign – vaginal portion of the cervix become soften
• Chadwick’s sign - cervix, vagina, and vulva becomes darken
• The presence of human chorionic gonadotropin (HCG) in the blood and urine
• During implantation of the embryo in the uterus implantation bleeding occurs at third or fourth week after last menstrual period
• Increase in hormones levels causes darkening of the nipples and areolas and linea nigra due to hyper pigmentation.20