Physiology & Psychology

• Maternal physiological adaptations to pregnancy

• The placenta

• Psychology of pregnancy

Physiology 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.

TABLE 8-4. Ventilatory Function in Pregnant Women Compared with the Postpartum Period

  During Pregnancy

Factor 10 Weeks

24 Weeks

36 Weeks

Postpartum6-10 Weeks

Respiratory rate 15-16 16 16-17 16-17

Tidal volume (mL) 600-650 650 700 550a

Minute ventilation (L)

— — 10.5 7.5a

Vital capacity (L) 3.8 3.9 4.1 3.8

Inspiratory capacity (L)

2.6 2.7 2.9 2.5

Expiratory reserve volume (L)

1.2 1.2 1.2 1.3

Residual volume (L) 1.2 1.1 1.0 1.2a

a Significant increase or decrease compared with pregnant women.

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.

Nitrogen Balance (g/day)

Source Early pregnant

Late pregnant

Non-pregnant

Intake 12.03 12.19 11.88

Fecal 0.82 0.92 0.64

Urinary 10.52 9.02 10.56

Integumental 0.14 0.18 0.21

Retention 0.56 2.10 0.46

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

Nonpregnant

Early pregnancy

Late pregnancy

Total triglycerides 60 75 to 100 210

Total cholesterol 170 175 to 200 250

VLDL cholesterol 10 10 25

LDL cholesterol 105 100 to 125 150

HDL cholesterol 55 55 to 75 65

Lipids

Maternal Albumin

Week of Gestation 10 20 30 40

Serum Albumin g/L 32 29 28 28

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. TNF, 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

Placental vasculature                                                             

Reproduced with permission from: Vander, AJ, Sherman, JH, Luciano, DS. Human Physiology, 6th ed, McGraw-Hill, Inc 2001. p. 679. Original Figure

19-24. Copyright © 2001 McGraw-Hill. ©2007 UpToDate® • www.uptodate.com

Licensed to Univ Of Washington

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

Mechanisms of Nutrient Transfer Across the Placenta

Maternal to Infant Nutrient Transportation Across The Placenta

Substance Primary Mechanism

Water, electrolytes, urea, free fatty acids, steroids, fat soluble vitamins

Passive diffusion

Glucose Facilitated diffusion

Amino acids, water soluble vitamins, calcium, iron, iodine

Active transport

Globulins, phospholipids, lipoproteins

Pinocytosis and endocytosis

Water, electrolytes Bulk flow (due to changes in hydrostatic or osmotic forces), solvent drag

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.

Maternal Focus

Trimester

1 I’m pregnant!

2 There’s a BABY…..

3 I’m going to be a MOM

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

Jordan, cont.

• Identified concerns:– Men not recognized as parents but as

helpmates and breadwinners– Men felt excluded from childbearing

experience by mates, health care providers, and society

– Fathers felt that they had no role models for active and involved parenthood

Jordon’s Developmental Tasks of Fatherhood

• Accepting the pregnancy

• Identifying the role of father

• Reordering relationships

• Establishing relationship with his child

• Preparing for the birth experience

What about Dad? Psychosocial and mental health issues for new fathers. (Condon, 2006. The Australian First Time Fathers

Study)Tasks:

1. Developing an attachment to the fetus

2. Adjusting to the dyad becoming a triad

3. Conceptualizing the self as “father”

4. What type of father?

Effects of pregnancy planning status on birth outcomes and infant care (Kost et al. Family

Planning Perspectives, 1998)

• Analysis of 1988 NMIHS (n=9122) and NSFG (n=2548) data.

Effects of pregnancy planning status on birth outcomes and infant care (Kost et al. Family

Planning Perspectives, 1998)

Intended Mistimed Unwanted

LBW 5.1 6.5 9.7

SGA 9.5 11.3 13.7

Anynegativeoutcomes

15.6 20.4 25.5

Everbreastfed

59.9 46.6 36.1

Effects of pregnancy planning status on birth outcomes and infant care (Kost et al. Family

Planning Perspectives, 1998)

• “Knowing the planning status of a pregnancy can help identify women who may need support to engage in prenatal behaviors that are associated with healthy outcomes and appropriate infant care.”

Unintended Pregnancy

Post-Partum Depression – PRAMS

Washington State PRAMS

WA State PRAMS