Embryonic and Fetal Development

Gestational Age

Pregnancy is measured using

first day of a woman’slast menstrual period (LMP).

Gestational age starts on?

10 months

Women are pregnant for about 9 months, but because pregnancy is measured from a woman’s last menstrual period, a full-term pregnancy usually totals about?

• Fertilization

• Implantation

• Embryonic period occurs from the 3rd to the 8th week of development

• the three germ layers, ectoderm, mesoderm, and endoderm, gives rise to a number of specific tissues and organs.

• Development of nervous system.

1st Month Prenatal Development

3rd to the 8th week

Embryonic period occurs from the _________ of development

• Missed menstrual period

• Possible feeling of fatigue, feeling bloated, frequent urination, mood swings, nausea, and tender or swollen breasts

• Not all women get these symptoms

1st month changes in mother

• The heart has formed. Heart begins to beat faintly.

• Fingers and toes develop.

• The arms bend at elbows.

• External ears, eyes, eyelids, liver, and upper lip have begun forming

• The sex organs are the same in all embryos until the 7 th or 8 th week.

• If a gene triggers the development of testes, the embryo develops as a male. If there is no trigger, the embryo develops ovaries and becomes female

• Tail disappears.

2nd Month Prenatal Development

• Pregnancy symptoms more noticeable

• Breast tenderness, fatigue, frequent urination, heartburn, nausea, and vomiting usually get worse

• Produces extra blood during pregnancy, and heart beats faster and harder than usual to carry the extra blood

2nd Month changes in Mother

• The embryo develops into a fetus after 10 weeks.

• Bones begin hardening.

• Begins making spontaneous movements.

• Digestive organ begins to function.

• Kidneys start making urine.

• Posture becomes less curled and more upright.

• Fetus is 3 inches long and weighs 1 ounce.

3rd Month Prenatal Development

• Most symptoms from 1st and 2nd month continue and sometimes worsen

• Breasts enlarge and areolas become larger and darker

• Gains weight (about 2-3 lbs.)

3rd Month Changes in mother

• Hair begins to grow.

• Head is more erect.

• Sex organs are fully formed.

• Heart and blood vessels are fully formed.

• Fetus is 7 inches and weighs 5 ounces.

4th Month Prenatal Development

• Some of the symptoms from first 3 months begin to be relieved.

• Belly begins to be more prominent.

• Heartburns and constipation.

• Breast changes continue

• Increased blood flow

• Gains weight (3-4 lbs.)

4th Month Changes in mother

• Lanugo —a fine, downy hair — covers the body.

• Vernix caseosa, a greasy material, covers and protects the skin.

• Ears and nose begin to develop cartilage.

• Fingernails and toenails begin to appear.

• Can suck a thumb, yawn, stretch, make faces and grasp.

• Gender of fetus may be determined.

• Fetus is 12 inches long and weighs 14 ounces.

• Extremely preterm - born at or before 25 weeks of pregnancy

5th Month Prenatal development

• Fetal movements (quickening) are felt for the first time

• It may feel like flutters or butterflies in the stomach.

• Shortness of breath may improve.

• Breasts may start producing colostrum —tiny drops of early milk.

• Some women have Braxton Hicks contractions

• They feel like a painless squeezing of the uterus or abdomen. This is the uterus’s way of practicing for labor and delivery.

• Braxton Hicks contractions are normal and not a sign of preterm labor.

• Gains weight (3-4 lbs.)

5th Month changes in mother

a fine, downy hair — covers the body.

Lanugo

Vernix

a greasy material, covers and protects the skin.

• Cerebral Cortex of the brain rapidly develops

• Fetus is 16 inches long and weighs 3 pounds

• Fetus further develops fat until the end of the pregnancy

• By 26th – 27th week, CRL is about 9 inches

• Eyelids are usually fused together until 28th week

• By 28th – 29th week, CRL is about 10 inches

6th Month Prenatal development

• Symptoms from 4th and 5th month continue

• May experience backache

• Shortness of breath may improve

• Breasts may begin forming colostrum

• Some women may experience Braxton-Hicks Contractions (False Labor), as the uterus prepares for labor and delivery) (Normal, not a sign of preterm delivery) (Uterus prepares for labor and delivery

• Weight gain of 3-4 pounds

• Movements of the fetus may be felt

6th Month Changes in Mother

tiny drops of early milk

Colostrom

• Cerebral Cortex of the brain rapidly develops

• Fetus is 16 inches long and weighs 3 pounds

• Fetus further develops fat until the end of the pregnancy

• By 26th – 27th week, CRL is about 9 inches

• Eyelids are usually fused together until 28th week

• By 28th – 29th week, CRL is about 10 inches

7th Month Prenatal development

• Symptoms from earlier months continue

• Fetus is highly active, movements are felt

• Ankles may swell from standing

• Back pain is common

• Weight gain of 3-4 pounds

• Uterus continues to expand

• Dizziness may lessen

7th Month Changes in mother

• Fetus is 17 inches long and weighs 5 pounds

• By 29th – 30th week, CRL is about 10.5 inches

• In male fetus, testes begin to descend into scrotum by 30th - 34th week, completing on 40th week

• By 31st – 32nd week, CRL is about 11 inches • Lanugo begins falling off

• Fingernails extend beyond the fingertips

• Subcutaneous fat is stored for later use

8th Month Prenatal development

• Occasional headaches

• Backaches

• Heartburn

• Difficulty sleeping

• Weight gain of 3-5 pounds

• May experience difficulty breathing, as the uterus expands upward

• May get varicose veins or hemorrhoids

• Constipation

• May get stretch marks

• Braxton-Hicks contractions may continue

• May experience UI (Urinary Incontinence) due to pressure from the uterus on the bladder

• Hair may appear fuller and healthier due to hormones

8th Month Changes in mother

• Lanugo is shed

• Eyes have developed enough to constrict and dilate

• Organ systems actively function

• Fetus is considerably fatter, and skin is no longer wrinkled • Vernix is present

• Fetus settles into position for birth

• By 33rd – 34th week, CRL is about 12 inches • By 35th – 36th week, CRL is about 12.5 inches

9th Month Prenatal development

Position vs Presentation

“Position” refers to fetal orientation in the womb. “Presentation” refers to which part of the fetus is leading/closest to the birth canal

• Uterus has descended

• Heaviness in lower abdomen

• Difficulty holding urine

• Varicose veins

• Stretch marks

• Ankle swelling

• Trouble sleeping

• Shortness of breath

• Fatigue

• Weight gain of 3-5 pounds. Total: 20-29 pounds

• Due to the descent of the fetus into the lower part of the uterus, constipation and heartburn may be relieved

9th Month Changes in mother

• By 37th – 38th week, CRL is about 13-14 inches

• Fetus has a firm grasp

• On average, Neonate (Newborn) is around 18- 22 inches long and weighs around 7-8 pounds

• Nearly all of the venix and lanugo are gone

10 Month Prenatal development

• Most women give birth around this time

• By the end of the pregnancy, the uterus has expanded from the pelvis to the bottom of the rib cage

• Shortness of breath, heartburn, and constipation usually improve when fetus drops

• Difficulty holding urine

• Cervix begins to dilate, may experience sharp pains

• Afterbirth, placenta and other tissues are expelled

10 Month Changes in Mother