Week 4: Introduction to life stages preconception Preconception or peri-conceptional period: Period around the time of conception generally defined as the month before and the month after conception. Pregnancy stages represent a continuum, ·Fertility is achieved & maintained by carefully orchestrated, complex processes that can be from preconception to the post-partum period. Pregnancy diseases: preeclampsia diabetes Alterations of fetal growth, IUGR, macrosomia miscarriage infertility Effects in later life 1st trimester - disrupted by a number of factors related to body composition & dietary intake. Fetal period Preconceptional period Post partum period IMPLANTATION EMBRYOGENESIS PLACENTATION LMP -2 -1 12 40 1 Years conception Weeks of gestation delivery ·Oral contraceptives & contraceptive implants can adversely affect some aspects of nutritional status. ·Optimal nutritional status prior to pregnancy enhances the likelihood of conception & helps ensure a healthy pregnancy & robust newborn. Fertility-Actual production of children; Both underweight and overweight can affect fertility Fecundity-Biological ability to bear children Infertility-Absence of production of children (after 1 yr unprotected sex) Infecundity-Biological inability to bear children (after 1 yr unprotected sex) Infertility ~15% of couples are "infertile" - involuntarily childless Infertility increasing due to obesogenic environment Infertility vs infecundity - 40% of couples diagnosed as "infertile" will conceive within 3 years without use of technology Healthy couples have a 23% to 30% chance of conception within a given menstrual cycle 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 Subfertility Reduced level of fertility characterized by unusually long time for conception (over 12 months) ~18% of couples are subfertile Examples: - Having multiple miscarriages/ Sperm abnormalities/ Infrequent ovulation POCS (Polycystic ovary syndrome) health conditions Ovaries produce high levels of androgens PCOS can be managed with diet Associated with abdominal obesity and insulin resistance Foods with low CI Weight loss on <5% makes a difference Nutritional & health status directly before & during the first two months after conception influence embryonic development & the risk of complications during pregnancy Reproductive physiology Puberty -period in which humans become biologically capable of reproduction Ova -eggs 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 · Women born with life-time supply of ~7 million immature ova · ~ 400-500 ova will mature & be released during fertile years · Chromosomes in ova may be damaged by oxidation, radioactive particle exposure, & aging · Women >35 years more likely to have disorders related to chromosomal defects than younger women Phases of menstrual cycle Follicular Phase-(first half of menstrual cycle) - Follicle growth & maturation - Main hormones: Gonadotropin-releasing hormone (GnRH), Follicle-stimulating hormone (FSH), estrogen & progesterone Luteal Phase-(last half of menstrual cycle) - After ovulation - Formation of corpus luteum
- Jin estrogen & progesterone stimulate menstrual flow - Prostaglandins & cramps Impact of obesity on reproduction Exercise &