1st Trimester Health Resources

The first twelve or so weeks of your pregnancy are known as the first trimester. It is during these first twelve weeks that your body will undergo many major changes as it prepares itself to create and sustain a new life inside of you.

Though fertilization occurs n this trimester, the pregnancy has actually begun as soon as your ovulation cycle began.

Once the ovum (or egg) has been fertilized by sperm, formation of the embryo begins. Here are some good things to keep in mind as you begin this wonderful journey:

The facts on sperm

Though there are typically 200 million to 500 million sperm cells released per ejactulation, it is usually only one that fertilizes the ovum. Sperm are released in semen, a fluid that nourishes and activates the sperm. Semen is made in the seminal vesicles and the prostate gland.

Once the sperm reaches the ovum, the head of the cell fuses, and eventually penetrates the membrane of the egg.

A sperm count will count the number of sperm in a sample, and also looks at the shape and movement of the sperm as well as whether they are fully mature and capable of fertilization. If you are having problems conceiving, this test may be a necessity to discover any issues that could be present.


Once the sperm has joined with the ovum and the embryo has formed, the next step is the creation of a blastocyst. A blastocyst is an embryo that contains two different cell types and a cavity between the two filled with fluid.

On the surface of the blastocyst are cells that will eventually develop into the placenta. These are call trophectoderm. The inner cells (creatively called the inner cell mass will eventually become the fetus itself. The formation of this blastocyst begins around the fifth day after fertilization.

Tender Breasts

Because of hormones, your breasts are likely to start to react to your egg’s fertilization even before you miss your first period. Your body is already working with the assumption that you will be breastfeeding.

Because of fat, human females have breasts even when they are not pregnant or lactating. Pregnancy means that what you need to breastfeed replaces some of the fat in your breasts. Once you are finished breastfeeding, it can take a little while for the fat to return and your breasts to regain their previous size and shape.


During your first trimester, and throughout your pregnancy, you may be hesitant to take any drugs or medication and understandably so. While there are a few medications that can cross the placenta barrier and should be avoided, other medications have been tested and are safe.

Above all, it will be important in this initial pregnancy stage to speak with a doctor or fertility specialist and discuss your current medications and whether or not you should continue taking them. Your doctor should be able to recommend possible alternatives, if necessary.


first trimester


Midwives are people who assist with your pregnancy by providing prenatal care, care during the birth and postnatal care. They are trained in many aspects of medicinal practice and often have close relationships with doctors of fertility specialists who refer them. They can work at hospitals or work in a separate medical office. Some have their own businesses they run solely as a midwife.

You may be referred to a midwife along your pregnancy by a doctor or fertility specialist within the first trimester of your pregnancy.

Fetal heart rate

Your baby’s heart rate will usually begin at about 110 beats a minute and gradually increase. It is usual for a fetus to have a faster heart rate in the first trimester of pregnancy but by the end of the pregnancy, it should have leveled off between 110 and 160 beats per minute.

Ectopic pregnancy

During your first trimester, there is an extremely small chance of discovering that your pregnancy is ectopic (literally out of place). Ectopic Pregnancies usually occur in the fallopian tubes but can, in very rare instances, be embedded in the ovary or other places in the pelvis.

If you have pain or unexplained bleeding, you may have an ectopic pregnancy and need to see a doctor. Ectopic pregnancies always end early and unsuccessfully. If it is left untreated, it could cause a life-threatening hemorrhage or ruptured fallopian tube.

After an ectopic pregnancy, fertility may be greatly reduced and/or impossible due to damage to the pelvis or fallopian tubes. It is also recommended that you get tested for Chlamydia, an easily-treatable sexually transmitted infection with very few symptoms that has been shown to cause ectopic pregnancies in some cases.


Drinking alcohol during any trimester of pregnancy can lead to fetal alcohol syndrome, a permanent disorder affecting your baby’s physical and mental development.

There is also evidence that drinking alcohol during pregnancy leads to a higher chance of miscarriage. If you did drink alcohol before you knew you were pregnant, even to the point of being drunk however, don’t beat yourself up. The majority of babies are born healthy including babies of mother who drank before discovering they were pregnant.

Weight gain

Weight gain during pregnancy comes from more places than just your little addition. During pregnancy, you will gain about a pound between your breasts, an average of eight pounds throughout your body, and the placenta alone weighs over one pound.

In addition, your uterus will gain more than two pounds itself. The amniotic fluid inside will add about another two pounds and after all of the extra blood and lymphatic cells are added into this fun math equation, the extra weight totals about eight pounds.

All in all, you will probably gain between 22 and 28 pounds during pregnancy, but this number is closely related to your health, weight and metabolism before you are pregnant. As long as you are eating healthy, you shouldn’t worry too much about this weight as nearly all of it will drop off after your baby is born.

If you have any questions or concerns, please check with your doctor or fertility specialist.

Nuchal pad of skin

In the first trimester, you may be recommended to have a nuchal fold scan for your baby. This is a simple medical procedure where the fold of skin on the back of the neck is scanned for thickness. An increased nuchal fold (a collection of fluid at the back of the neck) can be an early indicator of Down’s Syndrome.


Almost all of your pregnancy will be commanded by hormones in your body. Hormones are chemicals which are created to circulate the blood and catalyze organs or organ systems to a specific action. Sometimes that action is making other hormones to travel to other parts of the body.

From the beginning of conception, hormones are manufactured in the ovary. In the first trimester (about the 10th week), the placenta will slowly assume responsibility for manufacturing these hormones.

The main hormone that will sustain your pregnancy is progesterone. As your pregnancy continues toward birth, the amount of progesterone increases. Another hormone that is crucial in pregnancy is oxytocin which tells your body to being labor. Oxytocin is manufactured in the pituitary gland which is just beneath the brain.

Due to the sickness and tiredness you are likely to experience, the first trimester has many terms and a lot of them we are not able to write on a family-friendly website.

It is usually the time that marks the highest amount of changes in your body and can be the most painful as well due to the dramatic changes in your body’s chemistry and physique. Knowing what to expect can help you prepare for these changes and have a more pleasant first trimester of your pregnancy.

Images from lumaxart.com, womenshealth.gov, cdc.gov, choosemyplate.gov, epa.gov