Pregnancy and Breastfeeding Chapter 17 BIOL 1400 Dr

Pregnancy and Breastfeeding Chapter 17 BIOL 1400 Dr. Mohamad H. Termos

Nutrition and fertility Malnutrition may cease ovulation and decrease sperm number and motility Malnutrition may result in an underdeveloped placenta or improper attachment to the uterine wall

Nutrition and Pregnancy - Malnourishment low -birth-weight infant - >20% of ideal body weight higher risk for gestational Diabetes and hypertensive disorders.

Structures of Female Reproductive System Reproductive organs are classified as essential or accessory Essential organs: gonads are the paired ovaries; gametes are ova produced by the ovaries: the ovaries are also internal genitals Accessory organs: - Internal genitals: uterine tubes, uterus, and vagina: ducts or duct structures that extend from the ovaries to the exterior - External genitals: the vulva - Additional sex glands such as the mammary glands

Ovaries - Nodular glands located on each side of the uterus above the fallopian tube and covered by the germinal epithelium - The ovaries contain follicles which contain the developing female gametes, the ova. Every month a mature egg or “ovum” is released from either the right or the left ovary during ovulation. This process that results in the formation of a mature egg is called oogenesis. - The ovaries are endocrine organs that secrete the female sex hormones (estrogens and progesterone)

Uterus: Functions - Part of reproductive tract, permits sperm to ascend toward uterine tubes. If conception occurs, an offspring develops in the uterus. The wall of uterus is composed of three layers: inner endometrium, middle myometrium, and outer layer of parietal peritoneum. The blood to the uterus is supplied by uterine arteries - Embryo is supplied with nutrients by endometrial glands until the production of the placenta. Placenta is an organ that permits exchange of materials between mother’s blood and fetal blood but keeps the two circulations separate - Myometrial contractions occur during labor and help push the offspring out of mother’s body

Uterus: Functions - If conception does not occur, outer layers of endometrium are shed during menstruation – Menstruation is a cyclical event that allows the endometrium to renew itself

Uterine Tubes, Fallopian tubes, or Oviducts - Uterine tube has three divisions: isthmus, ampulla, and infundibulum. - Serve as transport channels for ova and as the site of fertilization - Most of the times fertilization takes place in the fallopian tube. - Ectopic pregnancy: development of the fetus in a place other than the uterus

Vagina Structure of the vagina - Collapsible tube capable of distention, composed of smooth muscle, and lined with mucous membrane arranged in rugae - Hymen: a mucous membrane that typically forms a border around the vagina in girls before first sexual intercourse - Lining of the vagina lubricates and stimulates the penis during sexual intercourse and acts as a receptacle for semen - Lower portion of the birth canal. Transports tissue and blood shed during menstruation to the exterior

Vulva The vulva consists of the female external genitals: mons pubis, labia majora, labia minora, clitoris, urinary meatus, vaginal orifice, and greater vestibular glands. Functions of the vulva: -The mons pubis and labia protect the clitoris and vestibule - The clitoris contains sensory receptors that send information to the sexual response area of the brain - The vaginal orifice is the boundary between the internal and external genitals

Breasts - Estrogens and progesterone control breast development and breast size is determined by the amount of fat around glandular tissue - Mechanism of lactation: – Ovarian hormones make breasts structurally ready to produce milk – Shedding of placenta results in decrease of estrogens and thus stimulates prolactin – Prolactin stimulates lactation - Lactation can provide nutrient-rich milk to offspring for up to several years from birth; some advantages are the following: 1 - Nutrients, 2 Passive immunity from antibodies present in colostrum and milk, 3 Emotional bonding between mother and child

Female Reproductive Cycles The female reproductive system has many cyclical changes that start with the beginning of menses - Ovarian cycle: ovaries from birth contain oocytes in primary follicles in which the meiotic process has been suspended; at the beginning of menstruation each month, several of the oocytes resume meiosis; meiosis will stop again just before the cell is released during ovulation.

Female Reproductive Cycles - Menstrual cycle (endometrial cycle) is divided into four phases: – Menses – Postmenstrual phase – Ovulation – Premenstrual phase - Myometrial phase - Gonadotropic cycle

Control of female reproductive cycles - Hormones control cyclical changes - Cyclical changes in ovaries result from changes in gonadotropins secreted by pituitary gland. - Cyclical changes in uterus are caused by changes in estrogens and progesterone.

Control of female reproductive cycles - Low levels of FSH and LH cause regression of the corpus luteum if pregnancy does not occur; this causes a decrease in estrogen and progesterone, which triggers endometrial sloughing of the menstrual phase - Control of cyclical changes in gonadotropin secretion is caused by positive and negative feedback mechanisms and involves estrogens, progesterone, and the hypothalamus’s secretion of releasing hormones

Prenatal and Postnatal Prenatal period: period beginning with conception and ending at birth Postnatal period: period beginning with birth and continuing until death Human developmental biology: study of changes occurring during the cycles of life from conception to death

A New Human Life Production of sex cells: spermatozoa are produced by spermatogenesis; ova are produced by oogenesis.

Meiosis Special form of cell division that reduces the number of chromosomes in each daughter cell to one half of those in the parent cell - Mature ova and sperm contain only 23 chromosomes, half as many as other human cells - Meiotic division: two cell divisions that occur one after another in succession - During meiosis I, “cross over” occurs where genetic material is “shuffled” - Daughter cells formed by meiotic division I contain a haploid number of chromosomes - Meiotic division II: reproduces each of the two cells formed by meiotic division I and forms 4 cells, each with the haploid number of chromosomes

Production of sex cells Spermatogenesis: process by which primitive male sex cells become transformed into mature sperm; begins approximately at puberty and continues throughout a man’s life - Meiotic division I: one primary spermatocyte forms 2 secondary spermatocytes, each with 23 chromosomes - Meiotic division II: each of the 2 secondary spermatocytes form a total of 4 spermatids

Production of sex cells Oogenesis: process by which primitive female sex cells become transformed into mature ova - Mitosis: oogonia reproduce to form primary oocytes; most primary oocytes begin meiosis and develop to prophase I before birth; there they stay until puberty - Once during each menstrual cycle, a few primary oocytes resume meiosis and migrate toward the surface of the ovary; usually one oocyte matures enough for ovulation, and meiosis again halts at metaphase II - Meiosis resumes only if the head of a sperm cell enters the ovum

Ovulation and insemination - Ovulation: expulsion of the mature ovum from the mature ovarian follicle, into the abdominopelvic cavity, and then the uterine (fallopian) tube - Insemination: expulsion of seminal fluid from male into the female vagina; sperm travel through cervix and uterus and into uterine (fallopian) tubes

Fertilization (Conception) - Most often occurs in the outer one third of oviduct - Ovum attracts and “traps” sperm with special receptor molecules on its surface - When one spermatozoon enters ovum, ovum stops collecting sperm on its surface - The sperm releases its nuclear chromosomes into the ovum; proteins and RNA from the sperm enter the ovum to assist with early development - 23 chromosomes from the sperm head and 23 chromosomes in the ovum comprise a total of 46 chromosomes - Zygote: fertilized ovum; genetically complete

Prenatal Period Begins with conception and continues until the birth of a child Once zygote is formed, it immediately begins to divide

Prenatal Period: Placenta - Anchors fetus to uterus and provides “bridge” for exchange of nutrients and waste products between mother and baby - Also serves as excretory, respiratory, and endocrine organ - Placental tissue normally separates maternal and fetal blood supplies - Has important endocrine functions: secretes large amounts of human chorionic gonadotropin (HCG), which stimulates the corpus luteum to continue its secretion of estrogen and progesterone.

Prenatal Period: Periods of development - Gestation period: approximately 39 weeks; divided into three 3 -month segments called trimesters - Embryonic phase extends from fertilization until the end of week 8 of gestation - Fetal phase: weeks 8 to 39

Prenatal growth and development - The 1 st trimester (1 -12 weeks) is the most critical period for baby growth and development. - Malnutrition would irreversibly damage major organs such as brain and heart.

Prenatal growth and development Second trimester - Appendages are fully formed by the beginning of this phase - Fetus may still be affected by exposure to toxins - Mother’s breast weight increases by approximately 30% due to deposition of fat for breastfeeding

Prenatal growth and development Third trimester - At the beginning: fetus weighs about 2 to 3 pounds - Infants born after 26 weeks gestation have a good chance of survival - At 9 months: fetus weighs 7 to 9 pounds and is about 20 inches long

Birth, or Parturition Transition between prenatal and postnatal periods of life - Stages of labor: - Stage one: period from onset of uterine contractions until cervical dilation is complete - Stage two: period from maximal cervical dilation until the baby exits through the vagina - Stage three: process of expulsion of the placenta through the vagina

Birth, or Parturition Multiple births: birth of two or more infants from the same pregnancy; twins are most common. - Identical twins result from the splitting of embryonic tissue from the same zygote early in development - Fraternal twins result from the fertilization of two different ova by two different spermatozoa

Increased nutrient needs during pregnancy 1 - Increased Calorie needs - Average pregnancy requires approximately 350 - 450 extra k-calories/day during last two trimesters - Focus on high-quality nutrient-dense foods as increased kcal requirement is because of increased vitamin and mineral needs

Increased nutrient needs during pregnancy 2 - Adequate weight gain - Total weight gain goal averages 25 to 35 pounds 3 - Increased protein and carbohydrate needs 4 - Increased vitamin needs - 30% increase for most B vitamins - Folate (folic acid): needs increase by 50% - Deficiency associated with neural tube defects

Increased nutrient needs during pregnancy 5 - Increased mineral needs - Especially iron, zinc and iodine - Supplementation side effects 1) Nausea 2) Constipation 3) Decreased appetite

Food plan for pregnant women 1 - Base diet on the Food Guide Pyramid 2 - Use of prenatal vitamin and mineral supplements - Supplements typically contain: iron, folate, and zinc - Beware of too much Vit. A: < 3000 mcg per day - Toxicity can cause birth defects

Effect of alcohol on pregnancy outcome Fetal alcohol syndrome: - Poor fetal and infant growth - Physical deformities - Mental retardation - Defects in vision, hearing, and mental processing often develop

Effect of Caffeine on pregnancy outcome Caffeine - Decreases absorption of iron - May decrease blood flow to placenta - If excessive: spontaneous abortion. - Limit coffee, chocolate, tea, and soda or medications with caffeine

Physiological changes of concern during pregnancy 1 - Heartburn - Hormones produced by the placenta relax muscles in both the uterus and intestinal tract - Stomach acids slip up into the esophagus

Physiological changes of concern during pregnancy 2 - Constipation - Results from relaxed intestinal muscles - Perform regular exercise - Increase water, dietary fiber, and dried fruits - May need to re-evaluate amount of iron supplement - Increases risk of Hemorrhoids

Physiological changes of concern during pregnancy 3 - Edema - Placental hormones cause certain tissues to retain fluids - Blood volume expands during pregnancy; extra fluid causes swelling - Only a medical concern if also hypertension and protein in urine

Physiological changes during pregnancy 4 - Morning sickness - 70 - 85% of pregnant women experience nausea - May be related to the increased sense of smell - Can occur any time of day Treatment: - Avoid fried or greasy foods - Eat crackers or dry cereal before getting out of bed - Avoid large fluid intakes early in the morning - Eat smaller, more frequent meals - Iron in supplements may trigger - Mega doses of B 6 can help (10 -25 mg 3 -4 x/day) - Ginger- 350 mg 3 x/day

Physiological changes of concern during pregnancy 5 - Anemia - Maternal blood volume expands about 150%. - Red cell number decreases 20% to 30% - Physiological anemia of pregnancy due to hemodilution - Dietary iron deficiencies can cause anemia

Physiological changes of concern during pregnancy 6 - Gestational diabetes - Hormones synthesized by the placenta antagonize the action of insulin - Treatment: Diet counseling, regular physical activity and possibly insulin injections Risks to fetus and mother: - Large baby possibly requiring c-section - Increased risk for mother and baby to develop diabetes later in life - Increased maternal risk of developing preecplampsia

Breast-feeding 1 - Recommendations - ADA and AAP recommend exclusive breast feeding until 6 months and breastfeeding with infant foods until 1 year. - WHO adds recommendation to continue breastfeeding until 2 years. 2 - Producing human milk - Formation of milk-producing cells called lobules - Infant suckling stimulates production of prolactin hormone that maintains changes in breast - Milk contains substances synthesized in breast tissue and from maternal blood circulation

Breast-feeding 3 - Let-down reflex: - Oxytocin from the brain allows breast tissue to release milk from storage sites to nipple area - Without reflex, little milk is available - Inhibited by nervous tension, lack of confidence, fatigue - After lactation established, let-down becomes automatic

Nutritional qualities of human milk - Very different from cows milk. No cows’ milk for infants under 12 mo. old - Colostrum: Produced for first few days after birth. Yellowish, thick. Contains antibodies and immune factors. - Lactobacillus bifidus factor encourages growth of bacteria that limits growth of potentially toxic bacteria - Mature milk: - Protein is easily digested by infant and it binds iron, decreasing growth of iron-requiring bacteria - Lipids is high in linoleic acid and cholesterol needed for brain development. Rich in Omega-3 fatty acids (DHA) used for synthesis of brain, central nervous system, and eye tissues - Breast milk should supply enough fluid.