Fetal Development Month by Month

How babies come to be.

Guess how old I am?

How old am I?

Stages of Prenatal Development Day 1: Conception takes place 7 Days: tiny human implants into mothers uterus 10 days: mother’s menses stop 18 days: heart begins to beat 21 days: pumps own blood through separate closed circulatory system with own blood type

Stages of Prenatal Development 28 days: eye, ear, respiratory system form 42 days: brain waves recorded, skeleton complete, reflexes present 8 wks: all body systems present 9 wks: squint, swallows, moves tongue, makes fist 11 wks: spontaneous breathing movements, has fingernails, all body systems working.

Stages of Prenatal Development 12 wks: weighs one ounce 16 wks: genital organs clearly differentiated, grasps with hands, swims, kicks, turns, somersaults (still not felt by mother) 18 wks: vocal cords work; can cry 20 wks: has hair on head, weighs 1 lb., 12 inches long

Stages of Prenatal Development 23 wks: 15% chance of viability outside of womb if birth premature 24 wks: 56% of babies survive premature birth 25 wks: 79% of babies survive premature

First Month By the end of the first month, the embryo is about 1/10 of an inch long. The heart, which is no larger than a poppy seed, has begun beating.

First Month

Two 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 heart has divided into right and left chambers. Veins are clearly visible. Most vital organs are developed.

Two Months

Three Months Starting at eight weeks, your baby is called a fetus. By the end of the first trimester, the fetus is 2 1/2 to 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, hand, and fingers are fully developed. The nails on his fingers and toes are starting to develop

Four 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 thrilling kick (quickening).

4 months

Five Months If you have an ultrasound, you might see him sucking his thumb. By 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.

Five Months

Six 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 started to practice breathing movements. If you talk or sing, he can hear you. Fingerprints are formed.

6 Months

Seven Months By the end of the seventh month, your baby weighs about 3 1/2 pounds and is about 12 inches long. His body is well formed. Fingernails cover his fingertips. He may try to turn toward a source of bright light.

7 Months

Eight Months Your baby is gaining about half a pound per week, and layers of fat are piling on under his skin. He has probably turned head-down in preparation for his coming birth. He weighs between 4 and 6 pounds.

8 months

Nine Months Your baby is a hefty 6 to 9 pounds and measures somewhere between 19 and 22 inches. The lungs develop in preparation fro breathing and the head is now head-down. As he becomes more crowded, you may feel him move around less. The last few weeks, the baby “drops” in preparation for delivery – giving the mother a little breathing space.

Multiple Pregnancy Sometimes two or more babies develop in the same pregnancy; this is called multiple pregnancy. Multiple pregnancies are far less likely than single ones. Twins are more likely than triplets, and triplets are more likely than quadruplets. Becoming more common today because of the use of fertility drugs.

Multiple Pregnancy Frequency of twins is about 1 in 35 births. Likelihood of having 3 or more is 1 in 540 births. The number of twins continue to rise. Health of multiple births are concerning doctors because of low birth weights (under 3.3 pounds). Puts them at risk for severe vision, hearing, mental, and developmental disabilities.

Fraternal Twins Most Common 2 different eggs and different sperm Can be twins, triplets, or higher. May or may not be the same gender They look different.

Fraternal Twins

Identical Twins 1 egg and 1 sperm Fertilized egg splits into 2 different cells Always the same gender Look the same

Identical Twins

Conjoined Twins If the ovum doesn’t completely split, the babies will be conjoined twins. The bodies of these twins are joined in one or more places.

Conjoined Twins