The First Trimester for Mom

The First Trimester for Mom

As a woman learns she is pregnant, her body may have no outward signs.  This does not mean that nothing is changing.  There is so much happening within her that may not be visible to the naked eye.

The Conception

The first trimester begins on the first day of the last menstrual cycle. (This is the date that a birth team will use to predict an estimated due date.) The body sheds the lining of the uterus to prepare it again for the possibility of implantation.  This may involve cramping and mood swings as the hormones rebalance. Approximately two weeks from this date, the ovaries release a mature egg.  A sperm will penetrate this egg, and a pregnancy will officially be underway. Process division of fertilized cell. Isolated on black background  


As the egg develops into a zygote, and further into an embryo, the mother’s body will feel the changes; not through kicks or baby movements, but due to the hormonal shifts taking place. HCG levels will double approximately every 48 hours from the moment of conception until about the 10th week of pregnancy.  This is a hormone that is not present unless pregnancy occurs; therefore, the body will react to it until the hormone levels off.  HCG circulates through the body and is eliminated through the urine.  This is the hormone that pregnancy tests are looking for to confirm conception. Progesterone and estrogen are both increasing, also playing a part in all pregnancy signs and symptoms for Mom.  These hormones are being produced by the corpus luteum until about week 10 of pregnancy, when the placenta takes over.   Estrogen plays a key role in the development of the fetus, but it also has a significant part in the changes of the mother’s body.  Estrogen helps the uterus grow, maintains the uterine lining, increases blood circulation, and activates the production of other hormones. During the first trimester, the increase of estrogen causes the breasts to swell and feel tender, even changing the look of the areola and nipple, leaving them darker and larger. Elevated estrogen levels may also cause spider veins, nausea, increased appetite, post nasal drip, headaches, congestion, and skin changes including changes in skin's pigment.  Mothers who experience the ‘Pregnancy Glow’ can attribute it to estrogen! Progesterone relaxes all smooth muscles in the body.  This includes the uterus so that it can expand as the baby grows. Other symptoms caused by progesterone increase include lower than normal blood pressure and occasionally dizziness, diarrhea, reflux, belching, nausea, vomiting, gas, and constipation (to name a few). Progesterone can also increase hair growth all over the body. Progesterone leads to the relaxation of the blood vessels throughout the entire body, so many of the first trimester pregnancy symptoms are tied to these hormones.

Early Signs and Positive Pregnancy Test


Many women claim to feel symptoms of pregnancy as early as 7-10 days past ovulation.  There may be implantation spotting that occurs around this time.  Inside the womb, the egg has split and cells have doubled numerous times, forming the zygote version of the baby.  Hormone levels are climbing and the mother’s body may feel anything from cold and flu symptoms to body temperature changes.  Foods may smell or taste different, and the abdomen may be bloated.  If there is enough hormone circulating to cause true symptoms, a home pregnancy test should turn positive, even if it is light. The earlier you take a HPT, the fainter the positive result will be.  Each test brand requires a different amount of HCG hormone to be present in the urine, so waiting until the 4th week of pregnancy (2 weeks past ovulation) is highly recommended.

Scheduling an Appointment

It is important to begin interviewing your potential birth team so you feel happy with your decision.  While, the first appointment is not until about 10 weeks along, unless there is an appointment done to confirm pregnancy at an earlier date.  The first appointment, depending on gestation, may include hearing the baby’s heartbeat, which is always a monumental moment!

Body Changes

Bloating:  It is quite typical to see bloating occur between weeks 4 and 10.  This is due to the increase of hormones flowing through the body, but once the placenta takes over the production of hormones, the bloating should decrease.  A true ‘Baby Bump’ is not really visible until a mother is into the second trimester. Swollen Breasts: Often on of the first signs of pregnancy, the mother’s breasts will swell and become tender to the touch.

First Trimester Possibilities

Exhaustion: The body is working at exhausting levels to create the foundation of the healthiest fetus possible.  Even though a mother may not think she should be tired, it is quite common that she requires extra hours of sleep each day. Spotting: Most women believe that a miscarriage is inevitable when spotting occurs, but that is not the case. 20-40% of pregnant women will experience bleeding during the first trimester, but continue on to have a healthy pregnancy. Cramping:  Twinges and cramps are common and can be blamed on the round ligaments that are stretching and aiding in the growth of the uterus. Nausea/Vomiting: The increase in hormones circulating the body can cause nausea until the hormones level off. Typically by the end of the first trimester, nausea fades. Young caucasian woman is vomiting in the bathroom. Bulimia, sick concept.   Food Aversions/Cravings: The body is on hyper-sensitive mode throughout weeks 4-12 of pregnancy.  This includes smells, taste buds, and even food cravings. Increased Heartrate: Cardiac volume increases by about 40 to 50% from the beginning to the end of the pregnancy. Weight Gain: While the average weight gain during the first trimester is about 5 pounds, some women actually lose weight because of morning sickness and food aversions.

The ‘Safe’ Zone

The end of the first trimester marks what most women label ‘The Safe Zone.’  If a heartbeat is heard, and measurements are in normal range, the chance of miscarriage drastically decreases.  This is also the time that most people announce their pregnancies, as they have seen their doctor or midwife at least once and feel more comfortable in sharing the news. Miscarriage occurs in about 20% of all pregnancies.  There is not a direct cause that has been found, and typically, it cannot be prevented. Stressing about having a miscarriage is not productive, but living a healthy lifestyle is the best way to ensure you are doing everything to support a healthy pregnancy.

Things to Note

The first trimester is the most dramatic in terms of development for the baby.  Smoking, drugs (over-the-counter even) can severely play a role in wrongful development. In 2015, a study was released that shows the mother’s gut flora can affect the development of the fetal brain as early as the first trimester of pregnancy. It is of utmost importance that a mother takes care of her diet and works on healing her gut to encourage positive brain development.


  • Begin looking into childbirth education options, as some courses are 12 weeks in length.
  • Your current prenatal vitamin may not be the best option.  Learn about options, folate vs. folic acid, synthetic vs real, raw food versions.
  • If your job is labor intensive, consider letting your boss know about your pregnancy.
  • Learn about your maternity leave options, or plan out a budget to stay at home after giving birth.
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