Though it may sound odd, your first week of pregnancy is based on the date of your last menstrual period. Your last menstrual period is considered week 1 of pregnancy, even if you weren’t actually pregnant yet.
The expected delivery date is calculated using the first day of your last period. For that reason, the first few weeks where you may not have symptoms also count toward your 40-week pregnancy.
|Signs and symptoms||Timeline (from missed period)|
|mild cramping and spotting||week 1 to 4|
|missed period||week 4|
|fatigue||week 4 or 5|
|nausea||week 4 to 6|
|tingling or aching breasts||week 4 to 6|
|frequent urination||week 4 to 6|
|bloating||week 4 to 6|
|motion sickness||week 5 to 6|
|mood swings||week 6|
|temperature changes||week 6|
|high blood pressure||week 8|
|extreme fatigue and heartburn||week 9|
|faster heartbeat||week 8 to 10|
|breast and nipple changes||week 11|
|noticeable weight gain||week 11|
|pregnancy glow||week 12|
From week 1 to week 4, everything is still happening on a cellular level. The fertilized egg creates a blastocyst (a fluid-filled group of cells) that will develop into the baby’s organs and body parts.
About 10 to 14 days (week 4) after conception, the blastocyst will implant in the endometrium, the lining of the uterus. This can cause implantation bleeding, which may be mistaken for a light period.
Here are some signs of implantation bleeding:
- Color: The color of each episode may be pink, red, or brown.
- Bleeding: Bleeding is usually compared to your regular menstrual period. Spotting is defined by blood present only when wiping.
- Pain: Pain may be mild, moderate, or severe. According to a study of 4,539 women, 28 percent of women associated their spotting and light bleeding with pain.
- Episodes: Implantation bleeding is likely to last less than three days and doesn’t require treatment.
Avoid smoking, drinking alcohol, or using illicit drugs, which are associated with heavy bleeding.
Once implantation is complete, your body will begin producing human chorionic gonadotropin (hCG). This hormone helps the body maintain the pregnancy. It also tells the ovaries to stop releasing mature eggs each month.
You will likely miss your next period four weeks after conception. If you have an irregular period, you’ll want to take a pregnancy test to confirm.
Most home tests can detect hCG as soon as eight days after a missed period. A pregnancy test will be able to detect hCG levels in your urine and show if you are pregnant.
- Take a pregnancy test to see if you’re pregnant.
- If it’s positive, call your doctor or midwife to schedule your first prenatal appointment.
- If you’re on any medications, ask your doctor whether they pose any risk to your growing baby.
A higher basal body temperature may also be a sign of pregnancy. Your body’s core temperature may also increase more easily during exercise or in hot weather. During this time, you’ll need to make sure to drink more water and exercise cautiously.
Fatigue can develop any time during pregnancy. This symptom is common in early pregnancy. Your progesterone levels will soar, which can make you feel sleepy.
- The early weeks of pregnancy can make you feel exhausted. Make an effort to get enough sleep.
- Keeping your bedroom cool can also help. Your body temperature may be higher during the early stages of pregnancy.
Around weeks 8 to 10, your heart may begin pumping faster and harder. Palpitations and arrhythmias are common in pregnancy. This is normally due to hormones.
Increased blood flow due to the fetus happens later in pregnancy. Ideally, management starts before conception, but if you have an underlying heart problem, your doctor can help supervise low dosages of drugs.
Breast changes can occur between weeks 4 and 6. You’re likely to develop tender and swollen breasts due to hormone changes. This is likely to go away after a few weeks when your body has adjusted to the hormones.
Nipple and breast changes can also occur around week 11. Hormones continue to cause your breasts to grow. The areola — the area around the nipple — may change to a darker color and grow larger.
If you’ve had bouts with acne before your pregnancy, you may also experience breakouts again.
- Relieve breast tenderness by purchasing a comfortable, supportive maternity bra. A cotton, underwire-free bra is often the most comfortable.
- Choose one with varying clasps that gives you more room to “grow” in the coming months.
- Purchase breast pads that fit into your bra to reduce friction on your nipples and nipple pain.
During pregnancy, your body increase the amount of blood it pumps. This causes the kidney to process more fluid than usual, which leads to more fluid in your bladder.
- Drink about 300 mL (a little more than a cup) of extra fluids each day.
- Plan out your bathroom trips ahead of time to avoid incontinence.
Similar to symptoms of a menstrual period, bloating may occur during early pregnancy. This may be due to hormone changes, which can also slow your digestive system down. You may feel constipated and blocked as a result.
Constipation can also increase feelings of abdominal bloating.
Nausea and morning sickness usually develops around weeks 4 to 6. Although it’s called morning sickness, it can occur any time during the day or night. It’s unclear exactly what causes nausea and morning sickness, but hormones may play a role.
During the first trimester of pregnancy, many women experience mild to severe morning sickness. It may become more intense toward the end of the first trimester, but often becomes less severe as you enter the second trimester.
- Keep a package of saltine crackers by your bed and eat a few before you get up in the morning to help settle morning sickness.
- Stay hydrated by drinking plenty of water.
- Call your doctor if you cannot keep fluids or food down.
In most cases, high or normal blood pressure will drop in the early stages of pregnancy. This may also cause feelings of dizziness, since your blood vessels are dilated.
High blood pressure as a result of pregnancy is more difficult to determine. Almost all cases of hypertension within the first 20 weeks indicate underlying problems. It may develop during early pregnancy, but it may also be present beforehand.
Your doctor will take your blood pressure during your first visit to help establish a baseline for a normal blood pressure reading.
- Consider switching to pregnancy-friendly exercises, if you haven’t yet.
- Learn how to track your blood pressure regularly.
- Ask your doctor about personal dietary guidelines to help reduce blood pressure.
- Drink enough water and snack regularly to help to prevent dizziness. Standing up slowly when getting up from a chair may also help.
Smell sensitivity is a symptom of early pregnancy that is mostly self-reported. There’s little scientific evidence about smell sensitivity during the first trimester. But it may be important, as smell sensitivity may trigger nausea and vomiting. It may also cause strong distaste for certain foods.
One review looked at reports from 1922 to 2014 about the relationship between smells and pregnancy. The researcher found a trend that pregnant women tended to rate odors as more intense during their first trimester.
Weight gain becomes more common toward the end of your first trimester. You may find yourself gaining about 1 to 4 pounds in the first few months. The calorie requirements for early pregnancy won’t change much from your usual diet, but they will increase as pregnancy progresses.
In the later stages, pregnancy weight often spreads out between the:
- breasts (about 1 to 3 pounds)
- uterus (about 2 pounds)
- placenta (1 1/2 pounds)
- amniotic fluid (about 2 pounds)
- increased blood and fluid volume (about 5 to 7 pounds)
- fat (6 to 8 pounds)
Hormones can cause the valve between your stomach and esophagus to relax. This allows stomach acid to leak, causing heartburn.
- Prevent pregnancy-related heartburn by eating several small meals a day instead of larger ones.
- Try to stay sitting upright for at least an hour to allow your food more time to digest.
- Talk to your doctor about what may be safe for you and your baby, if you need antacids.
Many people may begin saying you have the “pregnancy glow.” The combination of increased blood volume and higher hormone levels pushes more blood through your vessels. This causes the body’s oil glands to work overtime.
This increased activity of your body’s oil glands gives your skin a flushed, glossy appearance. On the other hand, you may also develop acne.
Many of the body changes and symptoms of pregnancy you experience in the first trimester will start to fade once you reach the second trimester. Talk with your doctor about any symptoms that interfere with your daily life. Together, you can find relief and comfort for your pregnancy.
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