HUN 3403 Wk1 D2 Chapter 2 Preconception Nutrition Chapter Introduction Adequate health & nutrition status are needed for successful reproduction Inadequate health & nutrition status may disrupt reproductive capacity Preconception Overview: Infertility
~15% of couples are infertile 44% of couples diagnosed as infertile will eventually conceive without use of technology Healthy couples have a 20% to 25% chance of conception within a given menstrual cycle Preconception Overview: Miscarriage
Miscarriage: Loss of conceptus in 1st 20 weeks of pregnancy Causes of miscarriages: Defect in fetus Maternal infection Structural abnormalities of uterus Endocrine or immunological disturbances Preconception Overview: Subfertility
Subfertility: Reduced level of fertility characterized by unusually long time for conception ~18% of couples are subfertile Examples: Having multiple miscarriages Sperm abnormalities Infrequent ovulation 2020 Nutrition Objectives for the Nation Related to Preconception Reproductive Physiology
Key Terms: Pubertyperiod in which humans become biologically capable of reproduction Ovaeggs females produce & store within the ovaries Menstrual Cycle ~4 week interval in which hormones direct buildup of blood & nutrient stores within uterus; ovum matures & is released Reproductive Physiology
Development of female & male reproductive systems Begins during first months after conception & Continue to grow & develop through puberty Capacity for reproduction Establishes during puberty when hormonal changes stimulate maturation of reproductive system Reproductive Physiology: Ova and Women
Women born with life-time supply of ~7 million immature ova ~ ova will mature & be released during fertile years Quality of eggs decrease with age due to damage of cells DNA Reproductive Physiology: Sperm and Men
Sperm production begins during puberty, decreases somewhat after age 35 with production continuing to old age Female Reproductive System Male Reproductive System Hormonal Effects During the Menstrual Cycle
Gonadotropin-releasing hormone (GnRH) Stimulates pituitary to release FSH and LH Follicle-stimulating hormone (FSH) Stimulates maturation of ovum & sperm,production of estrogen Luteinizing hormone (LH) Stimulates secretion of progesterone and testosterone Hormonal Effects During the Menstrual Cycle
Estrogen Stimulates release of GnRH in follicular phase & follicle growth & maturation of follicle Stimulates vascularity & storage of glycogen & other nutrients within uterus Progesterone Prepares uterus for fertilized ovum, increases vascularity of endometrium, & stimulates cell division of fertilized ova Two Phases of Menstrual Cycle
Follicular Phase(first half of menstrual cycle) Follicle growth & maturation Main hormones: GnRH, FSH, estrogen, & progesterone Luteal Phase(last half of menstrual cycle) After ovulation Formation of corpus luteum in estrogen & progesterone stimulate menstrual flow Postaglandins & cramps Changes in the Ovary and Uterus Male Reproductive System
Interactions among hypothalamus, pituitary gland, and testes Process is ongoing rather than cyclic Androgens Testosterone Sperm are stored in the epididymis & released in semen Sources of Disruptions in Fertility
Adverse nutritional exposure Contraceptive use Severe stress Infection Tubal damage or other structural damage Chromosomal damage Factors Related to Altered Fertility Nutrition-Related Disruptions in Fertility
Undernutrition Weight loss Obesity High exercise levels Intake of specific foods & food components Undernutrition and Fertility
Undernutrition in women previously well-nourished Associated with a dramatic decline in fertility that recovers when food intake does Food shortages in countries have been accompanied by dramatic declines in birth rates Body Fat and Fertility Decreased fertility seen with low or high body fat due to alterations in hormones Estrogen & leptin Levels increased with high body fat & reduced with low body fat Both extremes lower fertility Infertility lower with BMI 30 Weight Loss and Fertility in Females
Weight loss >10-15% of usual weight decreases estrogen, LH, FSH Results in amenorrhea, anovulatory cycles, & short or absent luteal phases Treatment with fertility drug Clomid not effective in underweight women Weight Loss and Fertility in Males
Studies from World War II showed 50% decrease in malefertility during starvation Sperm viability & motility decrease with wt. 10 to 15% below normal & cease at wt. loss exceeding 25% of normal Oxidative Stress, Antioxidant Status, and Fertility
Oxidative stress in men Decreases sperm motility Reduces ability of sperm to fuse with an egg Oxidative stress in women Harm egg and follicular development Interfere with corpus luteum function Interfere with implantation of the egg Oxidative Stress, Antioxidant Status, and Fertility
Vitamin E Vitamin C Beta-carotene Selenium Found in vegetables and fruits. Protect cells of the reproductive system, including eggs and sperm Oxidative Stress, Antioxidant Status, and Fertility
Zinc status and Fertility in Men Plays important roles In the reduction of oxidative stress In sperm maturation In testosterone synthesis Has been investigated for potential role in infertility Plant Foods and Fertility
Low-fat, high fiber linked to irregular menstrual cycles Isoflavones (from soy) decrease levels of estradiol, progesterone, LH Also related to reduced sperm count in men Folate Status and Fertility
Intake by women of multivitamins with folate associated with decline in ovulatory infertility Intake by men of multivitamins with folate associated with improved sperm counts, motility, decreased abnormal forms of sperm Iron Status and Fertility
Rate of infertility lower in women who use iron supplements or iron from plant foods 14% of U.S. women enter pregnancy with inadequate iron stores Caffeine and Fertility
Study results are mixed on effects of caffeine Some studies have shown increased time to conception, others have failed to find effects If individuals choose to cut back on caffeinated beverages, it is their choice Alcohol and Fertility Alcohol may decrease estrogen & testosterone levels or disrupt menstrual cycles Studies on weekly drinks consumed show: 1-5 drinks 39% in conception >10 drinks 66% in conception Heavy-Metal Exposure and Fertility
High lead levels decreased sperm production, abnormal motility, shape Build-up of cadmium, molybdenum, manganese, boron, and other metals also affect male fertility Exercise and Fertility
Adverse effects of intense physical activity Delayed age at puberty Lack of menstrual cycles Appear to result from hormonal and metabolic changes Related to caloric deficits Reduced levels of estrogen Low levels of body fat Decreased bone density Nutrition During the Periconceptual Period
Very-early-pregnancy nutrition exposures Folate status prior to conception Neural tube defects Iron status prior to conception Iron deficiency is most common deficiency worldwide Recommended dietary intakes for preconceptional women Nutritional Disruptions MyPlate Recommendations for Preconceptional Women Example Menu for Preconceptional Women Nutritional Side Effects of Hormonal Contraception
Progestin only weight gain, decreased bone mineral accretion Combination contraceptives altered bloodlipid levels, increased blood and insulin levels, increased stroke Model Preconceptional Nutrition Programs
Preconceptional benefits of WIC Decreasing iron deficiency in preconceptional women in Indonesia Preconception Care: Preparing for Pregnancy
CDCs Preconception Health Initiative Recommends that primary health care visits include: Preconception health & pregnancy outcome education Screening for vaccination, weight, iron & folate status Assessment of alcohol use Management of diabetes & celiac disease Nutrition Care Process
Nutrition care standards developed by the Academy of Nutrition and Dietetics Part of new technology-based systems To facilitate health-services delivery Cost evaluation Electronic charting Coding and outcome measurement Nutrition Care Process
The Nutrition Care Process Step 1: Nutrition assessment Step 2: Nutrition diagnosis Step 3: Nutrition intervention Step 4: Nutrition monitoring and evaluation See Table 2.9 for summary