Physiological Changes During Pregnancy PDF

Physiological changes in pregnancy Dr.Banav Najeeb Objective Identify the changes in different systems of the body during pregnancy. Avoid misinterpretation of physiological changes of pregnancy as abnormal Identify the pathogeneses behind these changes. Appreciation of these differ...

Physiological changes in pregnancy Dr.Banav Najeeb Objective Identify the changes in different systems of the body during pregnancy. Avoid misinterpretation of physiological changes of pregnancy as abnormal Identify the pathogeneses behind these changes. Appreciation of these differences lead to appropriate management of ♦Fluid retention is the most fundamental change of pregnancy ♦Marked expansion in the ECF ♦Some increase in ICF ♦The total body water increase 6.5-8.5 L by the end of pregnancy. ♦Blood volume begins to increase at 6-8 weeks gestation and plateaus at 32-34 wks to allow blood flow to vital organs, fetus and to anticipate blood loss during delivery Factors causing fluid retention are: Sodium retention. Resetting of osmostat. Decrease thirst threshold. Decrease plasma oncotic pressure Plasma oncotic pressure determines to which the fluid pass into and out of capillaries. It is mainly determine by albumin concentration which decrease by 20% during pregnancy to (28-37 The average weight gain during is about 8-10 kg pregnancy. Wight gain is due to: Increase blood volume Fetus Placenta Liquor Uterus enlargement Breast enlargement Accumulation of fat and protein  Rates of weight gain varies across the trimesters of pregnancy: 1.6 kg gained in first trimester 0.45 kg per week in second trimester 0.4 kg per week in third trimester Woman with high BMI deliver infant with higher birth weight  Haematological changes Increase plasma volume 50% There is a state of haemodiliution leading to decrease haemoglubin, hematocrit, red cell count and plasma folate causing physiological anemia decrease blood viscosity 20%  ESR rises early in pregnancy MCV increase secondary to erythropoiesis MCHC remains stable Decrease in serum vit B12 due to active transportation to the fetus Serum iron& ferritin decrease due to increase The total WBC rises, because of increased polymorphonuclear leucocytes. Average value in third trimester 9,OOO/µL, while in the early days of the puerperium it elevated more. Platelet count usually remain stable throughout pregnancy, although may be lower than in the non pregnant state due to aggregation  increase in the platelet count have been reported in the first week postpartum this may attributed to Normal pregnancy is a hypercoagulable state  plasma fibrinogen level increase 50% increase in coagulant factors particularly I,V,VII,VIII, IX, X XII, and Von willbrand factor there is a reduction in the concentration of protein S and antithrombin III concentrations  Plasma fibrinolytic activity is decreased during pregnancy  which is significantly affected by placentally derived mediator  (plasminogen activator inhibitor II), but  Reproductive system  Amenorrhoea  Uterus enlarge due to hyperplasia and hypertrophy of the myometrial cells increasing the weight of the uterus from 50gm prepregnancy to 1000gm by term  The vaginal epithelium becomes thicker with excessive clear vaginal discharge without any soreness called leukorrhoea  Goodell's sign is the softening of the cervix due to increase fluid in cervix  Chadwick's sign is a bluish coloration of the mucous membrane of the cervix, vagina and vulva due to increased vascularity  The mucus glands of the cervix become distended and the cervical mucus becomes viscous and fills the endocervix forming a mucus plug, this has an abundance of leucocytes and acts as an antibacterial and mechanical barrier. Cardiovascular system enlargement of heart due to left ventricle hypertrophy Elevation of the diaphragm give rise to breathlessness The growing uterus pushes the heart upwards and to the left side. Auscultation: ejection systolic murmur can be heard in 96% which disappeared after pregnancy. increased loudness of both first and second heart sound, and third heart sound is audible in 84% of pregnant women by 20 weeks Palpitation is common and usually represent  Heart rate 10-15 beat/min Stroke volume(The amount of blood pumped by the left ventricle of the heart in one contraction) Cardiac output 40%(The heart rate * stroke volume) Total blood volume 40% Mean arterial pressure and peripheral resistance Both systolic and diastolic blood  After delivery, a shift of blood from empty uterus into maternal circulation called autotransfusion causes an increase 10-20% in the cardiac output. This period is risky for patients with heart diseases Strock volume, heart rate and cardiac output remain elevated for the first 2 days postpartum Cardiac output can vary depending on the uterine size and maternal position. While the pregnant woman in supine position the enlarged gravid uterus can cause aorto- caval compression and reduced cardiac filling leading to an underestimation of cardiac function and can cause supine hypotension and Normal findings on ECG in pregnancy : ▶ sinus tachycardia ▶premature atrial and ventricular ectopic beat (benign dysrhythmias) ▶Q wave (small) ▶ depression of ST-segment ▶left-axis deviation  Gastrointestinal systeme Nausea and vomiting Constipation Indigestion due to delay gastric emptying Heartburn or dyspepsia Food craving Cholestasis due to marked atonicity of gall bladder together with high blood cholesterol level during pregnancy can lead to gall  Respiratory system Diaphragm is elevated A-P and transverse diameters of thorax increase Dyspnea is common in 60-70% The respiratory mucous membranes become vascular, edematous, and friable The voice may deepen Epistaxis may occur Hyperventilation and Respiratory Decrease total lung capacity  Increase Pulmonary blood flow O2 consumption increase 20% Tidal volume (volume of air inspired or expired at each breath) increase 40% Minute ventilation (volume of air inspired or expired in 1 min) increase 40% Decrease residual volume(air remain in the lung)  Increase PO2 and decrease in PCO2 to facilitate gas exchange between mother and fetus. Bicarbonate level decrease due to renal excretion The renal system  Renal blood flow increase 70% by 6 weeks gestation lead to increase GFR 50%  Increase in GFR 50% which lead to increase clearance of most substance e.g. urea, creatinine and uric acid lead to decrease their levels in the serum  Frequency of micturation  Glycosuria may developed is The smooth muscle relaxation due to progesterone effect and the pressure effect of gravid uterus predisposed the pregnant women in third trimester to hydronephrosis and hydroureter, urine stasis, UTI and pyelonephritis Endocrine system  From the beginning of conception there are dramatic increases in hormones produced by the placenta e.g HCG, oestrogen, progesteron and human placental lactogen(HPL). Total and free plasma cortisol increase due to Adrenal cortical hyperplasia. Pituitary production of prolactin, ACTH,TSH increase There is marked rise in secretion of the mineralocorticoid aldosterone in pregnancy. The secretion of FSH, LH, growth hormone is unchanged or reduced  Detection of hCG in the serum or the urine is the basis of pregnancy tests. Serum assays detect pregnancy at 8-12 days of ovulation whereas urine assays at 14-18 days of ovulation. After delivery at term hCG can normally be detected in maternal serum or urine for up to 4 wk.  Thyroid gland It increase in size by about 13% due to hyperplasia of glandular tissues causing physiological goiter TBG concentrations double during pregnancy & iodine requirements increased Increase TSH Increase Total T3,T4 Unchanged Free T3,T4 After mid-pregnancy Resistance to the action of insulin develops possibly via increased cortisol or hPL. leading to mild diabetogenic state Fasting concentration of insulin increase which cause lower fasting blood sugar in pregnant than non pregnant women in first trimester. progressively plasma glucose concentrations rise. Glucose crosses the placenta readily and Biochemical change Decrease plasma protein concentration particularly albumin which affect oncotic pressure and peak plasma concentration of certain drugs Increase alkaline phosphatase due to placental alkaline phosphatase Total plasma calcium decrease but ionized calcium is unchanged LDH either remain unalter or increase in small amount Liver enzyme ALT and AST in uncomplicated pregnancy lower than non pregnant state Increase Serum amylase Skeletal system: The relaxin hormone is responsible for both the generalized ligamentous relaxation and the softening of collagenous tissues. The lumbar spine demonstrates exaggerated lordosis Certain skeletal joints such as the pubic symphysis and sacroiliac widen or have increased laxity. Breasts And Lactation After the second month of pregnancy the breast progressively increase in size due to proliferation of glands and deposition of fat. The nipple becomes larger and more pigmented and erectile. By 16 weeks gestation a thick yellowish fluid (colostrum) may be expressed. The primary areola becomes larger and mor pigmented Later in pregnancy a secondary less pigmented areola develops around the primary areola. Hypertrophied sebaceous glands appear on the areola Skin changes Skin pigmentation in genetalia, face and abdomen e.g. chloasma & linea nigra Spider naevi & palmar erythema may occur (high estrogen) Striae gravidarum due to rapid and excessive stretching of the skin is accompanied by breaking of the underlying connective tissue, giving rise to the characteristic purplish depressions, these occur in the skin of the lower abdomen, buttocks, thighs and breasts. Striae of pregnancy are due to the increased secretion of adrenocortical hormones which cause a decrease in the collagen and ground substance of connective tissue and allows the subcutaneous fibrous tissue to rupture wherever he skin is overstretched. Following pregnancy the striae become silvery white in appearance( striae albicans). Thank you Mrs. Nadia is a 24-year-old, married nurse. She is arranging an appointment with a midwife, as she has just had a positive pregnancy test. Her last Menstrual Period was on 1st of January 2016; her cycles are usually regular at 4/28. This is her first pregnancy, and she has no significant medical or surgical history. Describe the Naegele rule, and calculate Mrs Nadia’s Expected Date of Delivery (EDD) using that method. Discuss the physiological changes in the cardiovascular system in pregnancy.