Preconception Nutrition and Reproductive Physiology PDF

CHAPTER 2: PRECONCEPTION NUTRITION FN 355: Nutrition Throughout the Life Cycle Instructor: Amanda Dahl, MS, RD, LD  Does Nutrition Affect Reproduction? YES!!! Adequate heath & nutrition status are needed for successful reproduction Inadequate health & nut...

CHAPTER 2: PRECONCEPTION NUTRITION FN 355: Nutrition Throughout the Life Cycle Instructor: Amanda Dahl, MS, RD, LD  Does Nutrition Affect Reproduction? YES!!! Adequate heath & nutrition status are needed for successful reproduction Inadequate health & nutrition status may disrupt reproductive capacity Conception may occur when nutritional status is poor Poor nutritional status compromises fetal growth & development and mother’s health  Preconception Definitions & Stats Fertility: Actual production of children Best applies to vital statistics (i.e. fertility rate) Fecundity: Biological ability to bear children Loading… Healthy couples have a 30% chance of conception within a given menstrual cycle Infecundity (infertility): Biological inability to bear children after 1 year of unprotected intercourse Affects 18% of couples in Western world  Preconception Definitions & Stats Miscarriage: Loss of conception in the first 20 weeks (spontaneous abortion) Causes of miscarriages: Defect in fetus Maternal infection Structural abnormalities of uterus Endocrine or immunological disturbances Subfertile: Reduced fertility characterized by unusually long time for conception Multiple miscarriages, low sperm count, infrequent ovulation Reproductive Physiology Reproductive systems develop in utero & continue growing in size and complexity until puberty Ability to reproduce occurs during puberty due to Loading… hormonal changes stimulating maturation of reproductive system Female Reproductive System Born with a lifetime supply of immature ova (~7M) (eggs) Stored in the ovaries 400-500 will mature and be released Chromosomal damage of ova may occur with age, oxidation, stress, radioactive exposure, etc. preparing for pregnancy Menstrual Cycle: ~4 week interval when hormones direct a buildup of blood & nutrients within uterus The purpose is to prepare the ovum for fertilization by sperm and the uterus for implantation of a fertilized egg  Figure 2.2 Changes in the ovary and uterus correlated with changing hormonal levels ovulation : When the egg is released. If a woman is not ovulating , ↑ regnancy cannot occur. Hormonal Changes during Menstrual Cycle Gonadotropin-releasing hormone (GnRH) Secreted by hypothalamus Stimulates pituitary to release FSH & LH Follicle-stimulating hormone (FSH) Stimulates maturation of ovum & sperm production Stimulates egg to be released from follicle Luteinizing hormone (LH) Stimulates ovulation and secretion of estrogen, progesterone, & testosterone Hormonal Changes during Menstrual Cycle Estrogen Stimulates release of GnRH in follicular phase and inhibits in luteal phase Stimulates vascularity & storage of glycogen & other nutrients within uterus Progesterone “progestational” set stage for fertilization to happen Prepares uterus for fertilized ovum, increases vascularity of endometrium, & stimulates cell division of fertilized ova Phases of Menstrual Cycle Follicular Phase—(first 14 days) Follicle growth & maturation Increase of LH causes ovum release from follicle: OVULATION no ovulation = no pregnancy Sunge Luteal Phase—(last 14 days) Formation of corpus luteum (formed from follicle; produces estrogen & progesterone) If not fertilized, in estrogen & progesterone stimulate menstrual flow Prostaglandins cause cramps & uterus contractions releasing stored blood & nutrients If fertilized, implants 8-10 days later Male Reproductive System Sperm production begins during puberty, but decreases after age 35 Lifetime production of sperm Loading… FSH and LH signal testosterone production by testes Sperm maturation then takes 70-80 days, then transported to epididymis Upon ejaculation, mix with other secretions to form semen Rich in zinc, fructose, Vitamin E  low or high levels of body fat will impact hormones which will impact Fertility Disruptions fertility or health of baby Nutrition and Fertility Nutrition primarily affects fertility by Altering the environment in which sperm and eggs develop Modifying hormone levels that involve reproductive processes Undernutrition Chronic undernutrition Primary effect: Low birth weight (LBW) infants with high death rates in the first year of lifemom's nutritional needs are met first before baby in womb Acute undernutrition Associated with a dramatic decline in fertility that recovers when food intake does Body Fat Levels Decreased fertility seen with low or high body fat due to alterations in hormones Estrogen, testosterone & leptin are produced by fat cells Women: levels increased with high body fat & reduced with low body fat Men: obesity lowers testosterone & increases leptin both extremes lower fertility Infertility lower with BMI 30 Higher BMI = more risks Obesity and Underweight Causes Obesity and being underweight cause menstrual cycle irregularities leading to infertility: Short or absent luteal phases (less than 10 days) Anovulatory cycles- ovulation doesn’t occur * absence of Amenorrhea- absence of menstrual cycle Men: Reduces sperm viability and motility& decreases sperm production quality and motility of sperm Excessive Exercising Delayed onset of menstruation in competitive athletes Abnormal cycles normally due to calorie deficits, not necessarily exercise amount Periconceptional Period “The time Periconceptional Period: the time to establish around conception representing a a state of critical time when nutrition and other optimal exposures can impact conception, health and pregnancy maintenance, and the nutritional growth, development and future health status is BEFORE of the offspring conception ” Preconception Counseling Primary health care visits should include: Preconception & pregnancy outcome education Screenings for vaccinations, wt, iron & folate status Assessment of drug & alcohol abuse Management of current diseases (DM, Celiac Disease, etc) CHAPTER 4: NUTRITION DURING PREGNANCY FN 355: Nutrition Throughout the Lifecycle Instructor: Amanda Dahl, RD, LD A FEW KEY TERMS… Infant Mortality: Death that occurs in the first year of life Reflects the general health status of a population LBW & premature infants at increased risk of death Infant Morbidity: Illness that occurs in the first year of life Liveborn infant: when a completely expelled or extracted fetus breathes, or shows any signs of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the cord has been cut or the placenta is still attached. NATALITY STATISTICS Loading… NATALITY STATS CONT’D ADVANCEMENTS IN TECHNOLOGY Loading… INFANT MORTALITY BY COUNTRIES REDUCING INFANT MORTALITY & MORBIDITY Improve birthweight of newborns Desirable birthweight = 3500-4500 g (7 lb. 12 oz. to 10 lb.) Infants born with desirable wt less likely to develop: Heart and Lung diseases Diabetes Hypertension STATUS OF PREGNANCY OUTCOMES TIMELINE BEFORE, DURING & AFTER PREGNANCY CHANGES IN “TERM” GUIDELINES early term (37 0/7 weeks of gestation through 38 6/7 weeks of gestation), full term (39 0/7 weeks of gestation through 40 6/7 weeks of gestation), late term (41 0/7 weeks of gestation through 41 6/7 weeks of gestation), postterm (42 0/7 weeks of gestation and beyond) PHYSIOLOGY OF PREGNANCY Gestational Age: calculated from time of conception (~38 weeks) Menstrual Age: calculated from LMP (~40 weeks) Loading… Includes 2 nonpregnant weeks MATERNAL PHYSIOLOGICAL CHANGES MATERNAL CHANGES ANABOLIC: (0-20 weeks) Mother’s body is “building” in order to increase capacity to deliver blood, oxygen, and nutrients to fetus 10% of fetal growth occurs CATABOLIC: (20+ weeks) Stored energy and nutrients delivered to fetus 90% of fetal growth occurs HORMONAL CHANGES Human Chorionic Gonadotropin (hCG) Stimulates corpus luteum to produce estrogen & progesterone until the placenta takes over after 2 months Stimulates endometrium growth Progesterone (“pro-gestational” hormone) Maintains implantation by keeping uterine lining thick Relaxes smooth muscles in uterus & GI tract Increases secretions from sweat glands Estrogen Helps uterus grow & thickens uterine wall Promotes breast growth HORMONAL CHANGES, CONT Human Chorionic Somatotropin (hCS) Alters mother’s metabolism to use more FA for energy Increases glucose availability for fetus Oxytocin Prepares uterus for contractions (before, during & after delivery) Prompts mammary glands to secrete milk THE PLACENTA’S ROLE… Umbilical cord connects Waste removal placenta to fetus Placenta expelled after birth Nutrient & gas exchange THE PLACENTA’S ROLE… STRUCTURE: Double lining of cells separate maternal & fetal blood (Rhesus factor): Rh- mothers must receive shot to protect against antibody formation to Rh+ fetus Acts as barrier to some harmful substances, although many still pass through NUTRIENT TRANSPORT Nutrients first used for maternal needs, then for placenta & last for fetal needs Underwt women need to gain additional weight during pregnancy Undernoursished mothers should increase nutrient amounts during pregnancy FETAL GROWTH AND DEVELOPMENT Growth: Increase in size 4 Stages of Growth through cell replication and Hyperplasia enlargement of cell size Cell number Development: Progression of Hyperplasia & physical hypertrophy and mental capabilities through Hypertrophy growth and differentiation of Cell size organs and tissues, and integration of functions Maturation Stabilization of cell number and size FACTORS AFFECTING FETAL GROWTH Availability of energy, nutrient, and oxygen Insulin-like growth factor-1 (IGF-1) is primary growth stimulator Promotes uptake of nutrients & inhibits fetal tissue breakdown Sensitive to maternal nutrition Levels decreased with undernourishment Low levels decrease muscle and skeletal mass & produce asymmetrical growth NEWBORN WEIGHT CLASSIFICATIONS LBW < 2500 g (5.5 lbs) VLBW