1 Week Pregnant: The First Week of Your Pregnancy

One week pregnant. This is the beginning of an amazing journey. In just one short week, so much has happened and will continue to happen as your baby begins to grow. It can be hard to believe that such a tiny being will soon be changing your life in so many ways, but it’s true!

If you’re like most women, you’re probably wondering what to expect during the first week of your pregnancy. Keep reading for a detailed breakdown of everything that happens during this crucial time.

Your baby at week 1

Your baby is still about two weeks shy of her conception date, but your body knows to prepare for her. The lining of your uterus is thickening in anticipation of a fertilized egg—a pregnancy! You may not even know when you become pregnant. When the egg implants in the uterus, you may notice a little blood spotting, called implantation, that may appear to be a light period.

How big is your baby at 1 week pregnant?

Your body is preparing itself for pregnancy even though there is no baby yet to measure. During the first week of pregnancy, a woman’s egg begins to mature, making it the largest cell in her body.

During the first days of pregnancy, you will enter the follicular phase of the ovarian cycle. Periods coincide with the start of this phase. During the ovulatory cycle, immature follicles are stimulated by a hormone called FSH or follicle stimulating hormone. By days 5 to 7 of your cycle, one egg has become dominant.

There is usually a stronger blood supply and a higher level of estrogen in the dominant egg. A thickening of the uterine lining is also stimulated by estrogen.As this dominant egg matures, it waits for ovulation during the follicular phase.

Week 1 of Your Pregnancy

This is the first week of your pregnancy… but you’re not even pregnant yet! Confused? It may seem like the first week of pregnancy when you find out you’re expecting, but in reality, you’re probably around 4 weeks pregnant. Yes, it has already started! Skip ahead and check out week 4 (Your OB will give you an accurate estimate during your first prenatal appointment). Understanding the LMP (last menstrual period) method for calculating pregnancy is tricky. Here’s a primer:

Your doctor will calculate your due date by counting from the first day of your last menstrual period, or LMP. Doctors use this date because many women just don’t know when they last ovulated. Try to think of it this way: Each time your body has a period, you’re preparing for pregnancy, so it makes perfect sense that the first day of your menstrual cycle fits in to figuring out your baby-to-be’s due date.

1 week pregnant belly size

During the first week of your pregnancy, you will not notice any noticeable changes in your body. This is because many women continue to menstruate for the first few weeks of pregnancy. Hormonal changes can cause fluid retention and bloating, which may make it appear that you have gained weight or have a small “baby bump.”

Pregnancy Begins Before Conception

Your pregnancy begins about two weeks before the actual conception. The first day of your last period counts toward the 40 weeks physicians use to chart your pregnancy (doctors call this the LMP, or last menstrual period). It might sound backwards at first, but every period you have is a potential pregnancy—at least that’s how your body sees it.

After an egg leaves the ovary and travels through the fallopian tube, it’s primed for fertilization. And your body readies itself for that possible pregnancy. During a 12- to 24-hour window as the egg is making this journey, it could be fertilized. The lining of the uterus builds up in anticipation. If the egg is unfertilized, the uterus lining will shed (this is menstruation) so that the body can prepare for the next egg—and the next potential pregnancy.

Monitoring Your Menstrual Cycle

To understand when you’re primed for pregnancy, you need to know a little bit about your menstrual cycle. The average woman menstruates every 28 days, explains Dr. Timothy R.B. Johnson, head of the Department of Obstetrics and Gynecology at the University of Michigan Health System.

The first day of your cycle begins when you notice blood coming from your vagina. Your period lasts a few days. About 14 days after you first started menstruating, your ovaries release another egg. In other words, you’re ovulating—this is a prime time to get pregnant. Over the next 14 days, or the second part of your cycle, the egg works its way to the uterus. If it goes unfertilized, the cycle begins again.

But charting this cycle is sometimes difficult. “Not all women have 28-day cycles,” explains Dr. Johnson. “Some women have 30-day cycles, or even 35; other women have shorter cycles.” So while your healthcare provider will give you an estimated due date based on your LMP during your first prenatal visit, only an ultrasound can give you an accurate picture of your baby’s exact arrival day.

Birth Control and Pregnancy

Birth control doesn’t increase your odds of infertility, although it may take you longer to get pregnant once stopping the contraceptive, advises Dr. Johnson. “It will probably take a couple of months before your cycle returns to normal.” That said, Dr. Johnson knows plenty of patients who got pregnant soon after they stopped taking the pill.

If you’re concerned that you’ve been off birth control without getting pregnant after those two months, it’s important to understand that from a medical standpoint, you’re not considered an infertility risk until you’ve gone at least one year with unprotected sex without a pregnancy.

Preparing for Pregnancy

To jumpstart a healthy pregnancy you might consider taking prenatal vitamins, drinking orange juice for folic acid, and getting some exercise. You may not even realize when you first become pregnant so refrain from drinking alcohol, taking drugs, or smoking cigarettes when you’re trying to conceive. Even prescriptions may be harmful to your developing baby, so be sure to speak to your doctor when you’re ready to start a family.

The importance of prenatal vitamins during pregnancy

During pregnancy, you need a greater amount of folic acid and iron. Why? Here are some reasons:

Folic acid prevents neural tube defects. These defects affect the fetal brain and spinal cord in a significant way. Preferably, you should begin taking extra folic acid three months before you become pregnant.
The placenta and fetus require iron to develop. The body uses iron to make blood to supply oxygen to the fetus. Additionally, iron helps prevent anemia, a condition in which the blood lacks healthy red blood cells

It’s important to consult your doctor to find out which are the best prenatal vitamins to take before pregnancy, and how to calculate your expected delivery date.

Can you feel symptoms first week of pregnancy?

Yes, it is possible to feel symptoms as early as one week after conception. Some women report feeling cramps, while others say they experience implantation bleeding or spotting. Other early pregnancy symptoms include fatigue, nausea, breast tenderness, and mood swings. However, it is also important to remember that not every woman will experience these symptoms and that they can be caused by other factors as well.

Conception, also known as fertilization, is when a sperm meets an egg. This typically occurs about 14 days after a woman’s period starts, according to the MOF (March of Dimes)

In its “Information for Teens About Conception and Pregnancy,” Planned Parenthood states that implantation begins about 6–7 days after conception. This is when the fertilized egg attaches to the lining of the uterus. This movement of the egg may break down blood vessels within the uterine wall, which may cause light bleeding and cramping.

Implantation bleeding

Implantation bleeding is a sign of pregnancy that happens when the blastocysts implants in the uterus. Implantation bleeding is different from regular menstrual bleeding because it involves spotting or light bleeding that may last for a few hours or days.

It typically occurs about 10 days after conception, or around the time of your missed period. Some women may experience implantation bleeding and not even know they are pregnant. If you have been trying to get pregnant, however, it can be a sign that the process is working.

Some women also have vaginal bleeding around implantation. This can be a sign that the embryo is attaching itself to the uterine wall, which may cause mild cramping and spotting. The bleeding usually stops within a few days.

Mild cramping

Some women feel mild cramps as the embryo attaches to the uterus wall. The cramps may be felt in the abdomen, pelvis, or low back area. They may feel like a pulling, tingling, or pricking sensation. Some women experience only a few minor cramps, while others may feel occasional discomfort that comes and goes over a few days.

The cramping usually starts a few days after implantation. It may be mild or severe and last for a few minutes to several hours. The cramps may feel like menstrual cramps, but they’re not related to menstruation. If the cramping is severe, it’s important to contact your doctor right away.

Possible Pregnancy symptoms in week 1

The first trimester (0 to 13 Weeks) of pregnancy is different for every woman, and every pregnancy. According to the Office on Women’s Health, one of the most common early signs is a missed menstrual period.

Common signs and symptoms of pregnancy

The most common early signs and symptoms of pregnancy might include:

Missed period. A week without a menstrual cycle might indicate you are pregnant if you are in your childbearing years. If you have an irregular menstrual cycle, this symptom can be misleading.
Tender, swollen breasts. In the early stages of pregnancy, hormonal changes can cause your breasts to become sensitive and sore. As your body adjusts to hormonal changes, the discomfort will likely decrease.
Nausea with or without vomiting. In the first two months after becoming pregnant, you may experience morning sickness at any time of the day or night. There are, however, some women who feel nausea earlier and some who never do. The cause of nausea during pregnancy is unknown, but pregnancy hormones are likely to play a role.
Increased urination. There is a possibility that you will need to urinate more frequently than usual. Pregnancy causes your body to produce more blood, which is processed by your kidneys and ends up in your bladder.

Fatigue. Among the early symptoms of pregnancy, fatigue ranks high. There is no scientific explanation for why pregnant women feel sleepy during the first trimester. During early pregnancy, progesterone levels may rise rapidly, contributing to fatigue.

Less common signs of early pregnancy

Besides the more common signs of early pregnancy, there are also some less common ones. There is no guarantee that these signs of pregnancy will occur, just as they might not occur with the most common symptoms. Symptoms will differ from person to person, so remember that every person is different.

The following are less common signs of early pregnancy:

Moodiness. Pregnant women can become emotional and weepy due to the flood of hormones in their bodies. It is also common to experience mood swings.
Bloating. During early pregnancy, hormonal changes can make you feel bloated, similar to how you feel at the beginning of a period.

Light spotting. One of the first signs of pregnancy might be light spotting. After conception, about 10-14 days after fertilization, the fertilized egg attaches to the lining of the uterus, leading to implantation bleeding. In most women, implantation bleeding occurs around the time of their menstrual cycle. It is, however, not common among all women.
Cramping. There are some women who experience mild uterine cramps during pregnancy.
Constipation. When your hormones change, your digestive system slows down, causing constipation.
Food aversions. It’s possible that you will become more sensitive to certain odors and tastes when you’re pregnant. Hormonal changes can explain these food preferences, as well as most other pregnancy symptoms.
Nasal congestion. A rise in hormone levels and blood production can cause your mucous membranes to swell, dry out, and bleed easily. As a result, you may feel stuffy or have a runny nose.

Can you have early pregnancy symptoms even if you’re not pregnant?

It’s important to keep in mind that many of these signs and symptoms don’t only happen during pregnancy. If you have some of these signs, you might start to feel sick or get your period. You can also be pregnant even if you don’t have many of these signs.

In any case, if you don’t get your period and have some of the above signs or symptoms, you should either do a home pregnancy test or see a doctor. If your home pregnancy test is positive, make an appointment with your doctor. If you can find out about your pregnancy as soon as possible, you can start prenatal care as soon as possible.

If you want to get pregnant or just found out you are pregnant, it’s a good idea to take a prenatal vitamin every day. Folic acid and iron are often found in prenatal vitamins to help your baby grow and develop.

Q & A

Got questions about Week 1? Other ladies have wondered this…

How to determine or calulate pregnancy weeks?

“When trying to understand gestational age standards, the best place to start is back in the days before ultrasound and ovulation detection, when the only thing we had to go on to determine due date was the last menstrual period. Ovulation occurs about day 14 of an average 28-day cycle. So conception on average occurs on day 14, or what we might call 2 weeks of gestation. It can be confusing to think that…” Read More

Can I be nauseous at 1 week pregnant?

It’s possible to feel nauseous at any point during pregnancy, but it’s most common in the first trimester. Nausea is often called “morning sickness,” but it can occur at any time of day. It may be accompanied by vomiting, but not always. There are many possible causes of nausea during pregnancy. It could be caused by hormonal changes, changes in diet or eating habits, or an underlying medical condition.

Not everyone experiences nausea and there are various levels of nausea. You can have nausea without vomiting—this changes from woman to woman.