Unit 4: Prenatal Development and the Newborn

How babies come to be-Conception

How do germ cells unite to create new life? Ovum are produced and stored by the woman’s ovaries. Inside the ovum is stored in a small sac called a follicle. Hormones cause follicles to grow and fill with fluid each month. Around the middle of the menstrual cycle, one ovum is released from the follicle (sometimes more than one is released). This is called ovulation.

The ovum (egg) is released, it travels toward the fallopian tubes The ovum (egg) is released, it travels toward the fallopian tubes. The uterus is the organ in which the baby develops and is protected until birth. At the time the ovum is released, hormones help the fallopian tube move to gather the egg. These hormones also prepare the uterus to receive and support a baby if conception occurs.

An egg goes down the fallopian tube after ovulation; if a sperm makes its way from the vagina through the uterus to the egg within 24 hours, conception is likely to occur.

Semen (over 100 million sperm) enters the woman’s body during intercourse. The sperm begin a journey to the ovum that lasts only minutes. Many sperm do not survive. Only a few hundred reach the fallopian tube. About a dozen sperm approach the ovum and try to break through its surface. Only one sperm successfully enters (or fertilizes) the egg. Once the sperm is accepted, no other sperm can enter the ovum. Conception has occurred and a zygote forms. When the sperm and egg form a single cell, it is called a zygote until it reaches the uterus in 3-4 days.

Conception- 2 germ cells (1 male-the sperm and 1 female-the egg) join together.

Video Clip: Conception Look Who’s Talking Intro Video Clip: Conception

Genetic Factors and the Unborn Baby These factors affect all stages of growth and development. Genetic factors influence the prenatal stage more than any other stage Genetics gives the cells instructions for family-like traits that will unfold throughout their life. Where does nature keep this important information? It is stored in DNA in threadlike structures called chromosomes.

Chromosomes and Genes Each baby receives 46 total chromosomes, which forms 23 pairs. Half from the mom, half from the dad. Each chromosome contains about 20,000 genes. These genes determine the individual traits the person will have. Human cells contain about a million genes. Sometimes one gene determines a trait, other times a group of genes determines traits.

Dominant and Recessive Traits People can pass on traits that don’t show up in them. This is because some traits are dominant and some are recessive. Dominant Recessive Those that always show in a person even if only one gene of the pair is inherited. Typically do not show in a person unless both genes are inherited. (Examples are eye color and hemophilia)

Sex Chromosomes Of the 23 pairs of chromosomes, 22 are alike in both males and females. The 23rd pair of chromosomes are called sex chromosomes. Females have the chromosome pair XX Males have the chromosome pair XY. When a male’s chromosome pair splits to form germ cells, some will be X and some will be Y. All the mother’s eggs will carry the X chromosome. If fertilized by a sperm carrying an X chromosome, the child will be female. If fertilized by a sperm carrying the Y chromosome, the child will be male. The father’s sperm always determines the sex of a baby.

Multiple Pregnancy Far less common than single pregnancies, multiple pregnancies do happen. Twins happen more often than triplets and triplets more often that quadruplets. Multiple pregnancies have become more common because of fertility treatments and older women having children. Twins frequency is about 1 in 35 births. Triplets is 1 in 540 births. Multiple pregnancies are often concerning as these births happen earlier and the babies have low birth weights. This puts them at risk for severe vision, hearing, mental and developmental disabilities.

Twins Identical Births Fraternal Births Mixed Types The most common multiple pregnancy, caused when multiple babies develop from 2 or more ova. Each ova is fertilized with a different sperm. The babies have different genetic make up. Each child in a fraternal birth has its own chorion. Children develop from a single ovum that was fertilized by a single sperm. The ovum split during the early days of pregnancy to produce 2 or more children. If the ovum does not completely split, the twins will be conjoined twins. Babies from an identical birth have the same DNA (genetic makeup). These babies are very similar in appearance. Fingerprints, palm prints, and footprints are similar but not exactly the same. Some identical twins can be mirror twins. They look the way you and our mirror image would look. Multiple pregnancies may be both identical and fraternal if 3 or more babies are born.

Prenatal Development : Many changes happen between conception and birth. The development that happens during this time is called Prenatal Development

What is the Germinal Stage ? The Germinal Stage is the first stage of prenatal development . This lasts about 2 weeks after conception

Prenatal Development by week : 1st Stage : The Germinal Stage What Happens? Cell divisions occurring Fertilized egg embedding in the wall of the uterus Amnion, placenta and umbilical cord begin to form

2nd Stage : The Embryonic Stage What happens ? 1. Internal organs like the heart , liver and brain start to develop 2. Tissue segments ( future vertebrae) in a spinal column forming 3. Limb buds such as arms and legs start appearing

3rd Stage : The Fetal Stage What happens? 9-40 weeks are all considered the “Fetal Stage” At 9 weeks the facial features start forming , limbs , hands , feet , fingers and toes start developing

Fetal Stage Continuation : At 12 weeks the eye brows and eyelashes start growing , and the heart beat is audible by stethoscope At 20 weeks the baby weighs 1lb , sweat glands start to form , head hair starts to appear and the skin starts developing

At 24 weeks the baby’s eyes start to mature , and taste buds start to develop At 28-40 weeks the baby is growing rapidly , body organs begin to mature and fatty tissue begins to form under the skin

Prenatal Care and Childbirth Chapter 5 Prenatal Care and Childbirth

Signs & Symptoms of Pregnancy -40 weeks A missing menstrual period Morning sickness and nausea Frequent urination Cravings Breasts enlarge Fatigue and dizziness A simple urine test or blood test from the doctor will show whether or not a woman is pregnant.

The embryo may float freely in the uterus for about 48 hours before implanting Upon implantation, complex connections between the mother and embryo develop to form the placenta.

Call the doctor if the following occur: Vaginal bleeding Sharp abdominal pain or cramping Loss of fluid from the vagina Severe or prolonged nausea or vomiting Frequent dizzy spells Painful urination High fever over 100 degrees F Vaginal discharge that is irritating

Other Considerations: No medications, including over the counter drugs, unless approved by your doctor. No drugs or alcohol No X-rays No saunas or hot tubs No vaccinations during pregnancy Avoid cats, cattle, sheep and pigs. They have a parasite that causes toxoplasmosis.

First month By the end of the first month, the embryo is about ¼ of an inch long. The heart, no longer than a poppy seed has begun beating. Head, mouth, liver and intestines begin to take shape.

2 months The embryo grows to about an inch long and has distinct, slightly webbed fingers. Veins are clearly visible. The placenta is already nourishing the baby through the umbilical cord. The hear has divided into right and left chambers. Veins are clearly visible. Most vital organs are developed.

3 months Starting at 8 weeks, your baby is called a fetus. By the end of the first trimester, the fetus is 2 ½-3 inches long and is fully formed. He has begun swallowing and kicking. All organs and muscles have formed and are beginning to function. The arms, legs, hands and fingers are fully developed. The nails on his fingers and toes are starting to develop.

Second Trimester- 4 months Skin-every woman’s body reacts differently to pregnancy. Oily, dry or scaly Stretch marks Facial skin may darken Emotions Need a few extra breaks or time to relax May experience mood swings, depression and bad dreams Feel baby’s movements

4 months Your baby is about 2 inches long and is covered with a layer of thick, downy hair called lanugo. The first outlines of the face are showing. His heartbeat can be heard clearly. This is when many mothers feel their baby’s first kick.

5 months If you have an ultrasound, you might see the fetus sucking his thumb. Bt the end of this month, your baby will be nearly 8 inches long and weigh almost a pound. The skull bones are the most important bones being developed at this time.

6 months Tiny eyebrows and eyelids are visible. There is a lot of evidence to show that the baby can hear the outside world. Your baby’s lungs are filled with amniotic fluid, and he has to start practice-breathing movements. If you can talk or sing, he can hear you. Fingerprints are formed.