First Trimester Pregnancy: Week 1 – Week 13

About 1st trimester pregnancy

Pregnancy is measured in trimesters, starting from the first day of your last menstrual period, totaling 40 weeks. The first trimester of pregnancy is week 1 through week 12, about 3 months. The second starts from week 13 to week 27 whereas the third trimester of pregnancy spans from week 28 till the birth.

Every week your body undergoes certain changes, however after fertilization, the egg that is fertilized develops into a microscopic ball of cells known as blastocyst, which implants on the uterus wall. A series of physical and hormonal changes in the body are triggered by this implantation.

After this, begins the embryonic stage that is the third through eight weeks of growth. The embryo develops most major organs of the body. During this development, the embryo is highly vulnerable to damaging substances such as infectious disease, alcohol and radiation.

Symptoms during 1st trimester pregnancy

Early pregnancy is the emotional stage of life; it brings lots of excitement and thrilling knowledge that you have created a new life. There are different symptoms of pregnancy, which takes a little time getting used to it.

These are some of the following symptoms of pregnancy:

• Lower abdominal cramps
• Food cravings
• Morning sickness 
• Breast changes
• Constipation
• Increased urination

Weeks during 1st trimester pregnancy

The following changes take place week by week:

• 1 week of pregnancy: In the first trimester certain changes takes place in the body before your baby actually starts growing. The first trimester is from week 1 to the end of week 12 and the second trimester starts from the week 13. The first week is actually your menstrual period, because the expected delivery date (EDD) is calculated from the first day of the last period.
• 2 week of pregnancy: At the beginning of the second week that is often around day 14 of a 28-day cycle you ovulate; one of your eggs is swept away from your ovary and into a Fallopian tube. The sperms that your mate ejaculates manage to swim from the vagina through the cervix, to the fallopian tube and penetrate the egg.
• 3 week of pregnancy: In the third week your baby is just a tiny ball that contains hundreds of cells that multiplies rapidly. At this time amniotic fluid begin to collect around your ball of cells in the cavity that would develop into the amniotic sac. This fluid cushions the baby till the next weeks and months ahead.
• 4 week of pregnancy: The fourth week is the beginning of the embryonic period. From now till the next 10 weeks, all the baby's organs will start to develop and some will even start to function. At this stage the baby is an embryo, just the size of a poppy seed, containing two layers epiblast and hypoblast, from which all the body part develops.
• 5 week of pregnancy: In the fifth week, the baby grows to the size of a sesame seed that resembles a tiny tadpole than a human. There are now three layers, endoderm, mesoderm and ectoderm. These layers will later form all the tissues and organs.
• 6 week of pregnancy: The sixth week is the major developments of the ears, nose and mouth. In the uterus there is an oversized head and dark spots, this is where the baby's nostrils and eyes form. The emerging ears are marked by tiny depressions on the head sides and arms and legs by protruding bud.
• 7 week of pregnancy: In the seventh week hands and feet emerge from developing arms and legs. They look like paddles, technically at this stage the baby is still considered an embryo and develops a small tail which is actually an extension of the tailbone.
• 8 week of pregnancy: Now in the eighth week webbed fingers and toes poke out from the baby's hands and feet, eyelids develops to cover the eyes, breathing tubes spread from his throat to the branches of the developing lungs and the tail disappears.
• 9 week of pregnancy: At the ninth week the embryonic "tail" disappears completely. The muscles, nerves and organs develop. The eyelids are fused shut and earlobes, nostrils and mouth appears more distinct.  However the sex organs cannot be identified for the next few weeks.
• 10 week of pregnancy: At the tenth week he is barely the size of a kumquat. The baby has now developed to the most critical portion. This is the beginning of the fetal period. At this stage the organs and tissues in the body rapidly matures.
• 11 week of pregnancy: At this stage the baby grows 1 1/2 inches long, about the size of a fig. After sometime the hands will soon open and close into fists and some of her bones also start to harden. The tiny movements start that look like water ballet.
• 12 week of pregnancy: The most dramatic development takes place in this week. If you prod your abdomen the baby will squirm in response but you cannot feel it. The intestines that have grown rapidly protrude into the umbilical cord, that starts moving into the abdominal cavity and the kidneys start excreting urine into the bladder. The baby grows 2 inches long, about the size of a lime as well as weighs about half an ounce. 
• 13  week of pregnancy: This is the latest week of your first trimester, and your danger of miscarriage is presently much lower than prior in pregnancy. Tiny bones are starting to structure in her arms and legs, the intestines are starting to move from the umbilical cord to the abdomen, and the vocal lines are well under development.

Baby's growth and development during 1st trimester pregnancy

During the three to four-day trip to your uterus from your Fallopian tube, the fertilized egg now known as zygote will split into 16 identical cells. The zygote is called a morula once it enters the uterus. After one or two days it will start delving into the lush lining of the uterus continuing its amazing growth and development. As you want your body to be in the perfect shape for baby's development do not forget to take a multivitamin every day that contains 400 micrograms of folic acid to reduce any risks of birth defects.