All weights are averages, and your baby may weigh more or less than the weight listed.
I believe that your baby’s life began at the time the sperm joined the ovum (egg). This occurred in one of your fallopian tubes, after 1/2 hour the new cell divided into 2 cells. It will continue to divide. It travels into the uterus where it attaches to the uterine wall.
During the first two weeks of your cycle, prior to you becoming pregnant, you body is preparing to ovulate. Hormones are stimulating your ovaries to produce and release an ovum. They are also signaling the endometrium to thicken, readying it to receive a fertilized egg. As this fertilized egg travels to the uterus, it will begin to divide. By the time it implants in the uterus, it has grown to over 100 cells with a fluid filled cavity. (called a blatocyst) it has two layers, the outer one will form the placenta, the inner one will become your baby. Once implantation occurs, your cervix gets wider and softer, and a thick mucous plug seals off the uterus to protect it from infection.
You may experience cramping and spotting when this happens. In the first month you may feel prickling, tingling sensation in your breasts due to increased blood supply particularly around the nipple area. You may have morning sickness, you will have an increase HCG in your blood and urine. The embryo is about 1 cm in length, with a head, tail fold and limb buds. A primitive central nervous system (CNS) forms.
Week 5- you may have a positive pregnancy test. You may be tired, have tender breasts, your nipples may begin to darken, and you may experience a metallic taste in your mouth or have morning sickness. You baby will implant into the uterus about this week, it will measure about 0.1-0.2 cm. the CNS, muscles and bones are in early developing stages.
To avoid problems: A lack of protein causes the placenta to adhere poorly to the uterine wall. Then the stress in labor can cause it to dislodge it.
By the end of the 7th week your baby will be about the size of a pea. The heart has divided into the right and left chambers and the primary airways have developed in the lungs.
By the 8th week you can tell the nose on the baby, eyelids have begun to form. The bronchi (the tubes that go from the trachea to the lungs) are beginning to branch out. Arms grow longer. The baby is now about 2-5 cm in length.
During weeks 4-8 all major organs are laid down in primitive form. There are early movements and the external genitalia is present but can’t yet tell the sex.
The kidneys begin to function between the 8-12 week.
Week number 9 your baby’s ears are forming more exterior. Feet and hands continue to form.
The baby will pass urine at 10 weeks. By the 10th week the baby is now considered a fetus! By the end of the 10th week the babys organs and systems are all formed, and now just continue to develop and grow. The baby is 1.25-1.70 inches in length and weighs just under a quarter of an ounce.
By week number 11 it is 1.75-2.4 inches in length and weighs about 0.3 ounces.
By week number 12 the baby is 1/2 ounce and is 2.5 inches in length. You can hear the heart beat now. The pituitary gland is starting to produce hormones, such as growth hormone, prolactin, corticotropin and others. There are now bone formations, Finger nails continue to grow, the baby is developing hair. Fingers and toes are fully separated.