CHILD CARE & DEVELOPMENTChapter 4

Pregnancy

CONCEPTION

Cell – the smallest unit of life; able to reproduce itself

Germ cells – the cells involved in reproduction; one from the male, one from the female

What are the male and female germ cells called?

CONCEPTION

Sperm – male germ cell

Ovum – female germ cell

Conception – the joining of the sperm and ovum

CONCEPTION

Zygote – the single cell that results from the joining of the sperm and ovum, otherwise known as the fertilized egg

Sex chromosomes – make up the 23rd pair; sex determined by this pair; XX = female, XY = male

MULTIPLE PREGNANCY

Multiple pregnancy – two or more babies develop in the same pregnancy

Frequency of twins in U.S. is 1 in 35 births Likelihood have having three or more babies is 1

in 540 births Becoming more common due to women using

fertility drugs as well as older women having children

Many babies in multiple births are born early and have lower birthweights

TWINS

Fraternal twins – when multiple babies develop from two or more ova fertilized by different sperm, each child has a different genetic make-up; the most common type of multiple

Identical twins – when multiple babies develop from a single ovum, fertilized by a single sperm, that splits; babies may have the same genetic make-up or be very similar in appearance

TWINS

PRODUCTION OF TRIPLETS

See page 119 in book

One egg set = all identical

Two egg set = two identical, one fraternal

Three egg set = all fraternal

STAGES IN DEVELOPMENT

Prenatal development – takes place from conception to birth; divided into three stagesGerminal stage – from conception to two

weeks; baby called a zygoteEmbryonic stage – two weeks to eight

weeks; baby called an embryoFetal stage – 9 weeks to birth; baby

called a fetus

STAGES IN DEVELOPMENT

Germinal stage – from conception to two weeks; baby called a zygoteCell division occursFertilized egg embeds in wall of uterusAmniotic sac, placenta, and umbilical cord

form

STAGES IN DEVELOPMENT

Embryonic stage – two weeks to eight weeks; baby called an embryo Heart, liver, lungs, digestive system, and brain

develop Tissue segments in spinal column form Limb buds appear Ears and eyes begin to form

STAGES IN DEVELOPMENT

Fetal stage – 9 weeks to birth; baby called a fetus 9 weeks

Facial features form Limbs, hands, feet, fingers, and toes develop

12 weeks Muscles form Teeth and vocal cords develop Eyelids and nails appear

16 weeks Lanugo (hairlike growth) appear Heartbeat audible by stethoscope Eyebrows and eyelashes grow

STAGES IN DEVELOPMENT

Fetal stage – 9 weeks to birth; baby called a fetus 20 weeks

Sweat glands form Head hair appears Vernix caseosa (waxlike substance) covers body Skin develops

24 weeks Eyes mature Taste buds develop

28-40 weeks (Rapid growth) Lanugo (hairlike growth) disappears Fatty tissue forms under skin Body organs mature

STAGES IN DEVELOPMENT

Amniotic sac – surrounds the cells to protect the baby until birth

Placenta – an organ filled with blood vessels that develops against the wall of the uterus; the umbilical cord grows out from the placenta

Umbilical cord – contains three blood vessels that connect the child with the placenta; nourishes the baby, removes wastes

STAGES IN DEVELOPMENT

Quickening – movements felt by the mother around four and five months; the baby is turning, moving its head, pushing with its hands and feet

Linea Nigra – dark vertical line running along belly button due to the increase of the pigment melanin (from increase of estrogen); happens in ¾ of all pregnancies