Changes during the First Trimester

First Trimester Timeline

Contrary to popular belief, pregnancy is not an even 9 months in length. The process is actually measured on a 40-week timeline. The beginning of pregnancy is commonly calculated from the beginning of your last menstrual period, meaning pregnancy actually starts two weeks before your baby is conceived.

Determining your due date is important for several reasons. Obviously, it helps set expectations for baby’s arrival. But it also helps your doctor know when to perform certain tests and estimate if baby is growing correctly.

Your due date is an estimate. In fact, on average, women can expect to deliver one to four days after their due date. It all goes back to a method developed in the early 1800s that counts 280 days from the first day of the women’s last period.

You will hear several terms used throughout pregnancy. Here are definitions of time:

  • Gestational age or menstrual age: This is considered the days between the first day of your last period and your estimated due date (280 days or 40 weeks). This is the age most healthcare professionals use to discuss pregnancy.
  • Ovulatory age or fertilization age: This begins the day of conception. Full-term is considered 38 weeks or 266 days.
  • Trimester: There are three trimesters in a pregnancy, each lasting about 13 weeks.
  • Estimated date of confinement (EDC): Your due date. Named so because noble women would be confined to their room with aids toward the end of their pregnancy.

The first trimester lasts about 13 weeks, although you are not even pregnant the first two weeks of that time period. Fertilization and implantation occur around the second week of the 40-week pregnancy timeline. The following 11 weeks are when your baby’s development is most rapid.

Your Baby during the First Trimester

After conception, you baby is in the embryonic stage. All major systems and organs begin to form including the neural tube (which will become the brain and spinal cord), the digestive and urinary systems, and the heart and circulatory system. By the 12th week, your baby is in the fetal stage. Limbs have developed, and fingers and toes are webbed but visible. Even fingernails and toenails have begun to form.

During the first trimester, bones have begun to develop and the jaw is developing quickly. Significant progress has been made regarding your baby’s head and face: The eyes, nose, mouth and ears are distinct, and tooth buds have started to form.

Additionally, the external genital organs are developed and could be distinguishable outside the womb. Your baby is in constant motion, even though he or she will not be big enough for you to feel it for several more weeks.

Because all major organs and systems are being formed this trimester, exposure to damaging substances, including drugs, tobacco, alcohol, and toxins, should be completely avoided. By the end of the trimester, these entities are fully formed, but your baby is still too small to survive on its own outside the womb. He or she is still counting on you for support and growth into a fully formed baby.

By the end of your first trimester, your baby will be about the size of a plum.

Your Body during the First Trimester

While you are likely not showing much on the outside, your body is experiencing many changes.

Your uterus continues to grow and may begin putting pressure on your bladder, causing frequent urination. The uterus may also press on the digestive tract, causing constipation. An increase in progesterone causes the muscular contractions in the intestines to slow and, combined with other pregnancy factors, increases likelihood that the mother will experience heartburn, indigestion, constipation or gas.

Moods may change quickly because of extra hormones in the body and the mother’s own feelings about the upcoming transition. Hormones may also play a role in increased episodes of morning sickness, nausea and sometimes vomiting. Your body will become fatigued more easily as you continue to build a new life in your womb.

Changes in Breasts While Pregnant

During pregnancy, your breasts will go through phases that are completely normal. Your hormones may cause them to grow larger; some women gain well over 1.5 lb. in each breast. They may also grow tender and extremely sensitive. Your nipples and areolas will darken and grow larger as you get closer to your due date. Many believe this happens so your baby can locate the source of food when their eyesight is not fully developed. You will also notice dark veins along your breasts. This is caused by increased blood flow.

Investing in one or two maternity bras that provide good support is a good idea. If your breasts increase greatly in size, consider supporting them at night as well. A cotton sports bra will do the trick.

An important note: while your breasts are growing and changing during pregnancy, it is still important to perform self exams about every four weeks. Breast cancer is uncommon in women under 35, but it does happen. If you are over 35 and considering becoming pregnant, talk to your medical care provider about a mammogram before getting pregnant. If you do find a lump, it may be a clogged milk duct, common in pregnant women. These lumps are red, tender and hard to the touch. You can relieve them with a warm compress and massage. If you find a new lump and do not believe it to be a clogged duct, consult with your doctor.

All About Bras

As previously mentioned, your breasts will change drastically during pregnancy. You will likely need to buy one or two new bras to get you through the experience. Many women opt to purchase a bra they can use before and after baby is born, meaning you will want to consider nursing bras. These bras have a clip at the top corners, which can be easily opened to feed baby when nursing. Other than that, they are normal, supportive bras, so they work during pregnancy, too.

Here is what to look for in a maternity/nursing bra:

  • Good support
  • Deep band beneath the cups
  • Wide straps
  • Comfort
  • Flexibility
  • No underwires (they can decrease milk supply)
The first trimester is a good time to learn the basics about cord blood banking and begin to decide what is best for your family

Skin Changes During Pregnancy

An onslaught of hormones and the need to stretch leads to many changes in skin during pregnancy. (Seriously, what isn’t changing at this point?). Here is a guide to understanding what is changing, what is normal, and what may warrant a second eye.

Color changes: Melanin cells in your skin dictate your skin’s pigmentation. Hormones produced during pregnancy may kick these cells into overdrive, producing more pigmentation (causing darker or lighter skin than before pregnancy). Women of light brown skin who live in regions with intense sun exposure more often develop these patches.

Itchy patches: Because your skin is stretching, it will likely become dry and itchy. Moisturize daily, drink water and ensure you are including omega-3 fatty acids in your diet. Fish, olive oil, almonds and macadamia nuts contain this healthy nutrient.

If the itching becomes severe or unbearable, talk to your physician. You may have developed a rare condition known as cholestasis of pregnancy or intrahepatic cholestasis of pregnancy (ICP). Itching usually begins in the palms and soles of the feet then spreads to the rest of the body, but no rash is present. Treatment includes anti-itch creams and UVB light treatments, and the condition usually subsides a few days after giving birth.

Chloasma: Irregular brown patches appear on the face and neck and may be referred to as mask of pregnancy. Most often, they disappear or fade after delivery. Many pregnant women develop chloasma after exposure to the sun, and women of Asian, Hispanic, North African, Indian and Middle Eastern backgrounds are more prone to the condition. To prevent spots from forming, stay out of the sun or wear protective block and clothing while in it.

Plaques of Pregnancy: These red, itchy bumps begin on the tummy and spread to the lower body, then the arms and legs. This rash is the most common skin condition pregnant women experience and is most common in white women. It is believed to be caused by rapidly stretching skin, which damages the tissue and causes inflammation. Because of this, women who gain a lot of weight or who are expecting multiples may be at greater risk. It is most common in first pregnancies and resolves within weeks after delivery. It also does not usually come back with future pregnancies. If you experience this itchy rash, talk to your healthcare provider. He or she will recommend some home remedies to try or a prescription as a last resort.

Pemphigoid Gestationis: This condition is rare, occurring in 1 in 50,000 pregnancies. It begins with itchy blisters forming around the belly button or elsewhere on the body. It may occur during the second half of pregnancy or flare up during delivery or immediately after baby’s birth. It does, however, often resolve on its own. Try oatmeal baths or talk to your doctor about anti-itch creams.

While these skin changes may seem scary or, more accurately, annoying and insufferable, they are not dangerous to your baby. Discuss a treatment plan with your medical team to relieve symptoms. If something does not look or feel right, always consult your physician.

While your baby is growing and your body is changing, you will continue to gain weight. Let’s look at how to stay healthy during the first trimester.

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