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Physiology & Psychology. Maternal physiological adaptations to pregnancy The placenta Psychology of pregnancy. Physiology of Pregnancy. Systematic Adjustments to Pregnancy. Cardiovascular Respiratory Urinary.
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Physiology & Psychology • Maternal physiological adaptations to pregnancy • The placenta • Psychology of pregnancy
Systematic Adjustments to Pregnancy • Cardiovascular • Respiratory • Urinary
Cardiac output during three stages of gestation, labor, and immediately postpartum compared with values of nonpregnant women. All values were determined with women in the lateral recumbent position.
Mean glomerular filtration rate in healthy women over a short period with infused inulin (solid line), simultaneously as creatinine clearance during the inulin infusion (broken line), and over 24 hours as endogenous creatinine clearance (dotted line).
King J. Physiology of pregnancy and nutrient metabolism. Am J Clin Nutr 2000;71 (suppl):1218S-25S
Adjustments in Nutrient Metabolism • Goals • support changes in anatomy and physiology of mother • support fetal growth and development • maintain maternal homeostasis • prepare for lactation • Adjustments are complex and evolve throughout pregnancy
General Concepts 1. Alterations include: • increased intestinal absorption • reduced excretion by kidney or GI tract 2. Alterations are driven by: • hormonal changes • fetal demands • maternal nutrient supply
3. There may be more than one adjustment for each nutrient. 4. Maternal behavioral changes augment physiologic adjustments 5. When adjustment limits are exceeded, fetal growth and development are impaired.
Birth weight of 11 children born to a poor woman in Montreal; 8 children were born before receiving nutritional counseling and food supplements from the Montreal Diet Dispensary and 3 children were born afterward.
6. The first half of pregnancy is a time of preparation for the demands of rapid fetal growth in the second half
7. Alterations in maternal physiology facilitate transfer of nutrients to the fetus.
Hormonal Adjustments • Changes in over 30 different hormones have been detected in pregnancy • Estrogens: increase significantly in pregnancy, influence carbohydrate, lipid, and bone metabolism • Progesterone: relaxes smooth muscle and causes atony of GI and urinary tract • Human Placental Lactogen (hPL): stimulates maternal metabolism, increases insulin resistance, aids glucose transport across placenta, stimulates breast development
Late gestation is characterized by: • Anti-insulinogenic and lipolytic effects of Human chorionic somatomammotropin, prolactin, cortisol, glucagon) Which Results in: • Glucose intolerance, insulin resistance, decreased hepatic glycogen, mobilization of adipose tissue
Maternal Nutrient Levels • Increased triglycerides • Increased cholesterol • Decreased plasma amino acids & albumin
Maternal Plasma volume increases ~ 40% • range 30-50% • nutrient concentration declines due to increased volume, but total amount of vitamins and minerals in circulation actually increases.
Mean hemoglobin concentrations ( — ) and 5th and 95th ( — ) percentiles for healthy pregnant women taking iron supplements
Embryonic Development • In early gestation Embryo is nourished by secretions of the oviduct and uterine endometrial glands • Uterine secretions include growth factors (e.g. TNFa, epidermal growth factor) that promote placental growth • Poorly nourished women and obese women at risk for aberrations in embryonic and placental development • Congenital anomalies • Adverse outcomes later in pregnancy (e.g. PIH) • Before implantation, blastocyst divides into embryonic cells and placental cells
Relationships of structures in the uterus at the end of the seventh week of pregnancy.
The Placenta • 10-12 weeks is the period of placentation • Rapid early growth prepares way for fetal growth • Trophoblast cells use same molecular mechanisms as tumors, but are highly regulated and controlled
Placental Functions • Maintains immunological distance between mother and fetus • Special endocrine organ: “transient hypothalamo-pituitary-gonadal axis” • Responsible for exchange of nutrients, gases & metabolic waste products between maternal and fetal circulation
Placental Architecture • Maternal and fetal blood do not mix: “placental barrier” • Fetal blood flows through capillary networks within highly branched terminal chorionic villi • Maternal blood flows through intervillous space • Uterine arteriols bring blood in • Uterine venules drain blood
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Placental Capacity Increases During Gestation • Expression of transporters increases • The “brush border” microvilli develop to: • increase surface area • impede maternal blood flow • Flow through the placenta at term is 500 ml/minute
Fetal to Maternal Transport • Carbon dioxide • Water & urea • Signaling Molecules: Hormones, cytokines, others
Factors Affecting Placental Transfer • Placental size • Diffusion distance – • diabetes and infection cause edema of the villi • distance decreases as pregnancy progresses and fetal needs increase • Maternal-placental blood flow • Blood saturation with gases and nutrients
Factors Affecting Placental Transfer (cont) • Maternal-placental metabolism of the substance • Disorders in expression or activity of nutrient transporters • Maternal use of tobacco, cocaine, alcohol
Metabolic Functions of the Placenta • Glycogen synthesis: from maternal glucose & stored • Cholesterol synthesis: placental cholesterol is precursor for placental progesterone and estrogens • Protein production: rises to 7.5 g per day at term • Lactate: produced in large quantities and needs to be removed
Endocrine Functions • Placenta Produces Peptide hormones • Human Chorionic gonodotrophin (hCG) - secreted early and helps to maintain synthesis of progesterone • Human placental lactogen (hPL): increase supply of glucose to future by decreasing maternal stores of fatty acids by altering maternal secretion of insulin • Insulin-like growth factors (IGF): IGF signaling system is a major regulator of growth in fetus and infant
Endocrine Functions • Steroid hormones • Progesterone: produced by placenta, needed to maintain non-contractile uterus • Estrogen: produced by placenta drives many processes in pregnancy • Glucocorticoids: placenta regulates fetal exposure
Emerging Understandings • Cytokines & Inflammatory molecules are produced by the placenta as well as adipocytes • Adverse outcomes in obese women may be associated with imbalances due to overproduction from both sources • “In pregnancy complicated with obesity or DM, continuous adverse stimulus is associated with dysregulation of metabolic, vasular and inflammatory pathways.”
The Known and Unknown of Leptin in Pregnancy (Hauguel-de-Mouzon, Am J Obstet Gynecology, 2006) • Maternal plasma leptin levels rise in pregnancy • Leptin is produced by placenta • Overproduction of placental leptin is seen with diabetes and htn in pregnancy • Umbilical leptin levels are biomarker of fetal adiposity • “Leptin may be sensitive to maternal energy status and coordinate metabolic response accordingly.” (King, Ann Rev Nutr, 2006)
Psychology of Pregnancy • Psychosocial tasks • Rubin • Leaderman’s tasks • Fathers • Stress and Depression
Developmental Tasks of Pregnancy (Rubin, 1984) • Seeking safe passage for herself and her child through pregnancy, labor, and delivery. • Ensuring the acceptance by significant persons in her family of the child she bears. • Binding-in to her unknown baby. • Learning to give of herself.
Lederman, RP. Psychosocial Adaptation in Pregnancy, 2nd Ed. 1996 • Developmental Tasks of Pregnancy • acceptance of pregnancy • identification with motherhood role • relationship to the mother • relationship to the husband/partner • preparation for labor • processing fear of loss of control & loss of self esteem in labor
Psychosocial adjustment during pregnancy: the experience of mature gravidas(Stark, JOGNN, 1997) • N=64 older gravidas (> 35), 46 younger gravidas (< 32) in third trimester • Lederman prenatal self evaluation questionnaire - examines conflicts for 7 steps • In general conflicts about maternal role were similar in both groups • Older gravidas had less concern about fear of helplessness and loss of control in labor - regardless of parity
Adolescents: PSYCHOSOCIAL FACTORS THAT INFLUENCE TRANSITION TO MOTHERHOOD (kaiser, 2004) • Gaining acceptance of the pregnancy in the family system • Awareness of the need to develop a sense of responsibility • Planning for a future that includes the baby • Viewing self as a mother
Laboring for Relevance: Expectant and New Fatherhood(Jordan, Nursing Research, 1990) • N=56 expectant fathers followed prospectively • Fathers reported: • grappling with the reality of the pregnancy and child • struggling for recognition as a parent from mother, coworkers, friends, family baby and society • plugging away at the role-making of involved fatherhood