Prenatal Development and Birth Chapter 4 Human Development

Prenatal Development and Birth: Chapter 4 Human Development & Learning

Hail Mary, full of grace! The Lord is with thee; blessed art thou among women, and blessed is the fruit of thy womb, Jesus. Holy Mary, Mother of God, pray for us sinners now and at the hour of our death. Amen.

9 months in 4 minutes The video linked above is amazing! I recommend watching it before you begin this chapter and again after you complete it. It emphasizes many of the important developments covered in this chapter. See how many you can spot! Also, the music is kind of epic.

Basic Baby Statistics The majority of fetuses are male (52%) and Chinese. Worldwide: 107 males are born to every 100 females. Natural ratio estimated at 105: 100. Almost 200 million births each year

China’s “One-child” Policy If you are not aware of China’s “One-child Policy” and the problematic gender gap it has created, please take some time now to inform yourself. What is it? What are some of the implications? (These sources will get you started, but are not considered “scholarly. ” I have posted three scholarly sources written by Hudson & den Boer, the sociologists mentioned in the second link, on Blackboard. )

From Zygote to Newborn Prenatal development is divided into three main periods: Germinal Period (0 -2 weeks) Embryonic Period (3 -8 weeks) Fetal Period (9 weeks-birth)

Timing and Terminology of Pregnancy • • Pregnancy begins at conception, which is also the starting point of gestational age. Zygote does not become an “embryo” until about two weeks later, and pregnancy cannot be confirmed until implantation. Some obstetricians date onset of pregnancy from the date of the last menstrual period (LMP), about 14 days before conception. Beginning of Pregnancy • Length of Pregnancy • Full-term pregnancies last 266 days, or 38 weeks, or 9 months. • Using LMP, this is 40 weeks, or 10 months. Trimesters Pregnancy is often divided into three-month periods called trimesters rather than germinal, embryo, fetal. Due date • Doctors assign a due date based on LMP, but only about 5% of babies are born on that date. • Babies born between three weeks before or two weeks after are considered “full term. ” • Early babies now called pre-term, late babies called postterm.

Why speak in trimesters? Dividing prenatal development into germinal, embryonic and fetal periods focuses primarily on physiological changes in the unborn child. The division of prenatal development into trimesters may better reflect experiential differences in the mother. For example: Morning sickness and fatigue are most common in the first trimester. Many women begin to “show” (i. e. , they begin to appear pregnant) in the second trimester and many also experience increased energy, relief from morning sickness, etc. During the third trimester, the baby may be very active; women may experience things like backache, difficulty finding a comfortable sleep position. There may be marked breast enlargement and possibly breast discharge (i. e. , colostrum, an early form of breast milk), increased vaginal discharge, “spotting” (i. e. , small amounts of bloody discharge) may occur; some women experience mild contractions (i. e. , Braxton-Hicks contractions) as the uterus prepares for labor.

Germinal: The First 14 days (see slide notes) Click here! Blastocyst: 1) cluster of cells 2) outer cells will become placenta 3) inner cells will become embryo. Placenta: organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply

The germinal period refers to the time between fertilization and implantation into the uterus; it may not take exactly 14 days. The ovum (i. e. , egg) is usually fertilized in the Fallopian tubes, which are small tubes that lead from the ovaries—where eggs are released- to the uterus, but fertilization may occur in the upper uterus. The uterus is a hollow, muscular organ located in the female body between the bladder and the rectum. In a normal pregnancy, the fertilized egg, called a zygote, becomes implanted in the nutrient rich lining of the uterus where it is nourished and grows. Pregnancy tests work by detecting human chorionic gonadotropin (h. CH), a hormone which increases upon implantation and helps the zygote grow, so pregnancy tests will not read “positive” before implantation. h. CH levels may take longer to reach detectable levels in some women than in others, so it make take longer to detect pregnancy. In a “tubal” or “ectopic” pregnancies, which account for an estimated 2% of pregnancies, the fertilized egg implants somewhere other than the uterus (e. g. , the Fallopian tubes or cervix). It is extremely rare for ectopic pregnancies to continue to term and, while many will resolve naturally, ectopic pregnancies can be dangerous to the mother. You can view some risk factors for ectopic pregnancy here.

Vulnerability for Spontaneous Abortion (non -induced miscarriage) Germinal period: At least 60% fail to grow or implant properly. Embryonic About 20% miscarry, most often there are chromosomal abnormalities. Fetal period: About 5% miscarry before viability at 22 or are stillborn. About 31% of all zygotes grow and survive to birth.

Embryonic Period: Weeks 3 -8 What happens during the embryonic period of prenatal development? Brain As nerves and muscles form links to the brain, the embryo now moves spontaneously, as the brain begins to move muscles. Facial Features Eyes and eyelids are developed. Eyes will continue to migrate to the front of the head, where they will eventually rest. Eyelids begin to grow together and are only half closed. External, middle, and inner ears are now fully formed. External ears will continue to migrate to the side of the head, where they will eventually rest. Urogenital membranes have developed into either External sex male or female organs, and ovaries or testicles are visible. Clitoris or penis begins to form, but organs distinguishing the embryo’s sex is difficult. Overall appearance The head is still disproportionately large but is erect and appears rounded. The neck is well defined. The tail will disappear by the end of this week. Cartilage begins to turn into bone. The ectoderm layer is replaced by the beginnings of skin. The body becomes evenly rounded, due to the growth in the abdomen. Intestines The intestines begin to move from the umbilical cord to the embryo’s body cavity. Arms, hands and fingers Arms are well formed, longer, and can bend at elbows and move forward. Fingers elongate and digits are fully separated. Each finger has three digits, and the thumb has two digits. Brain Facial Features Intestines External sex organs Arms, hands and fingers Overall appearance 13

1. 4 weeks: 1/8 inch, little tiny head taking shape 2. 5 weeks: 1/4 inch and already has a primitive pulsing heart !!! 3. 7 weeks: 2 ½ centimeters (a bit less than an inch) with eyes, nose, digestive system 4. 8 weeks: 1 inch long At the end of 8 weeks, all basic organs and body parts (except sex organs) are present!!!!!!

Fetal Period: 9 weeks-birth Third Month 9 weeks: Sex differentiation XY: SRY gene triggers development of male sex organs, testosterone helps shapes brain. XX: female sex organs develop Sex organs visible via ultrasound by end of 3 months. Brain development is significant Rule-of-thumb: 3 months, 3 ounces, 3 inches

Patterns of Prenatal Development Growth occurs following two patterns: 1. Cephalocaudal growth (head first) 2. Proximodistal growth (center of body first) So we see growth from the head down and from the center of the body out. The extremities are “late” to develop. This dual pattern of development continues postnatally.

Fetal Period: 9 weeks-birth Months 4, 5 & 6 Heartbeat becomes stronger Cardiovascular system more active Brain increases about six times in size Fingernails, toe-nails and buds for teeth form Hair grows Age of viability: 22 weeks after conception a fetus can survive outside the mother’s uterus if specialized medical care is available

Fetal Period: 9 weeks-birth Months 7, 8 & 9 Life outside the womb is possible at around 22 weeks, but requires intensive care and lifesupport. The difference between a preterm and fullterm newborn is the maturation of neurological, respiratory, cardiovascular systems

Fetal Period: 9 weeks-birth Months 7, 8 & 9 Physical development Lungs begin to expand contract Circulatory system matures Fetus usually gains about 4. 5 pounds Baby responds more and more to Mother’s voice, movements, mood.

Teratogens Teratogens: Agents and conditions, including viruses, drugs, and chemicals, that can impair prenatal development and result in birth defects or death. Behavioral teratogens: Agents and conditions and can harm the prenatal brain, impairing the child’s intellectual and emotional functioning.

Risk Reduction Determining Risk analysis is the science of weighting the potential effects of a particular event, substance, or experience to determine the likelihood of harm Timing of Exposure Critical period: the time when a particular organ or other body part of the embryo or fetus is most susceptible to damage by teratogens

Risk Reduction cont. Amount of Exposure Threshold effect: some things are harmless in small doses, but harmful once exposure reaches a certain level. Interaction effect Sometimes risk is greatly magnified when an embryo or fetus is exposed to more than one teratogen at the same time

Birth Defects from Teratogens: Time of Exposure and Effect on Major Organs Germinal Period 1 2 Main Embryonic Period (in weeks) 3 4 5 6 7 Fetal Period (in weeks) 8 9 16 32 38 Common site(s) of action of teratogens Highly critical period Less critical period Central nervous system Neural-tube defects Learning disabilities Mental retardation Heart Arms Legs Cleft lip Lips Ears Eyes Low-set malformed ears and deafness Cataract, glaucoma Teeth Enamel staining Palate Cleft palate Masculinization of female genitalia Sex organs Teratogens often prevent implantation Major congenital anomalies Source: Adapted from K. L. Moore & Persaud. 2003 Functional defects and minor anomalies 23

See Table 4. 4 (pp. 106 and 107) for a detailed chart of specific teratogens, their effects, and preventative measures.

It is very important, particularly during early pregnancy, for women to get enough Folic Acid. Too little folic acid is associated with neural tube defects. Folic Acid is contained in prenatal vitamins and can also be bought separately. For more, click on this link. Large amounts of green tea can interfere with the body’s ability to use folic acid. There is also concern about large amounts of Vitamin A during pregnancy. A book like this can be very helpful to help you keep track of what is important and/or dangerous during different stages of pregnancy.

A Normal, Uncomplicated Birth

Let’s think about… Labor contractions Delivery Placenta

Soooooo…. I am not qualified to say if it is actually beneficial to eat your own placenta; however, I’m pretty firm in my conviction that you there’s no good-enough reason to eat another person’s placenta. If you’re interested, you can check out these people, who are ostensibly BBQ-ing a human placenta for their friends and family: Yikes and Yikes again! What do you think? Real? Fake? Would you RSVP to this event?

Apgar Scale A quick assessment of a newborn’s health, given twice (at one minute and five minutes after birth). Five Vital Signs Score Color Heartbeat Reflex Irritability Muscle Tone Respiratory Effort 0 Blue, pale Absent No response Flaccid, limp Absent 1 Body pink, extremities blue Slow (below 100) Grimace Weak, inactive Irregular, slow 2 Entirely pink Rapid (over 100) Coughing, sneezing, crying Strong, active Good; crying

Birth Variations Roughly 1/3 of U. S. births occur via Cesarean section (i. e. , c-section). Fetus is removed through incisions in abdomen and uterus. There is controversy surrounding this. Induction Labor of labor: may be medically induced Also controversial.

Reflexes Brazelton Neonatal Behavioral Assessment Scales (NBAS; 46 behaviors, including 20 reflexes. Survival reflexes: Maintain oxygen supply Maintain constant body temperature Manage feeding

Reflexes Signaling State of Brain and Body Babinski reflex Stepping reflex Palmar grasping reflex Moro reflex Swimming reflex

Low Birth Weight (LBW) Less Very than 5 ½ lbs Low Birth Weight (VLBW) Less than 3 lbs. 5 oz. Extremely Less Low Birth Weight (ELBW) than 2 lbs. 3 oz.

Low Birth Weight cont. Low birth weight is associated with lagging physical and cognitive development. LBW risk factors: lifestyle choices (e. g. , cigarette smoking) maternal malnutrition multiple births prescription drugs unknown causes

Father’s Role Father’s presence Parental alliance Couvade: symptoms of pregnancy and birth experience by fathers.

Kangaroo Care This!

Postpartum Depression 10 -15% of women report symptoms of postpartum depression, a sense of inadequacy and sadness within a year after giving birth. Includes irritability, sleep and eating disruptions, sadness, feeling overwhelmed and inadequate as a mom, no interest or overly worried about baby.