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What to Expect in the 5th Week of Pregnancy

The Baby at 5 Weeks Pregnant

The embryo undergoes major changes at 5 weeks of pregnancy. All the cell layers are in place to create the baby's organs.

The embryo undergoes major changes at 5 weeks of pregnancy. All the cell layers are in place to create the baby's organs.

Five Weeks Pregnant

Symptoms of pregnancy may start to become evident around the fifth week of pregnancy. At this point, a woman's menstrual cycle will be one week late, and the embryo will be three weeks old from the point of conception.

Some foods may seem suddenly unappealing, even if they looked appetizing minutes before. Frequent trips to the bathroom due to frequent urination are another common complaint, along with overwhelming fatigue.

The baby is making dramatic changes this week, changing from a spherical configuration to a symmetrical, elongated gastrula. The cell layers responsible for all organ formation are present this week, and the embryo is particularly fragile and susceptible to environmental toxins.


Pregnancy Symptoms at Five Weeks

Pregnancy Symptoms at 5 Weeks

  • Nausea is a common complaint in early pregnancy. Not all women experience morning sickness, but a significant proportion of women will experience an aversion to some foods, nausea, or even vomiting.
  • Fatigue is often extreme in early pregnancy, and many women will find themselves taking naps or seeking an early bedtime.
  • The increasing size of the uterus and hormonal changes may cause frequent urination.
  • Bloating may make pants feel tight.
  • Some women will feel pinching and pulling sensations this week.
  • Sore breasts are a common complaint, due to the hormonal changes in early pregnancy.

Gastrulation Animation

Baby's Development in the 5th Week

Many significant changes occur to the embryo during its third week of life (the fifth week of pregnancy, as dated from the last menstrual cycle). The embryo completely changes shape, going from a spherical ball of cells to a flattened structure known as the gastrula.

The embryo forms three separate layers: the endoderm, mesoderm, and ectoderm. Organ systems like the lungs and intestines will arise from the endoderm, muscles and blood cells will come from the mesoderm, and skin and the nervous system are derived from the ectoderm.

The embryo also forms the primitive streak at this stage of development, which forms an axis for the embryo. This point is the beginning of gastrulation, and the mesoderm and endoderm migrate to their final positions within the embryo.

The notochord also forms during this week, along the axis created during gastrulation. The vertebrae (spinal column) will form around the notochord, which is present from day 17 of life until the beginning of the second month of development.

The neural crest and neural tube also form this week, as the neural plate of the embryo forms a neural tube. The neural crest cells will give rise to many cell types, including bone, cartilage, pigment, muscle and nerve cells.


Ultrasound at 5 Weeks of Pregnancy

An ultrasound shows the "double ring" sign of a gestational sac and yolk sac. This is commonly seen on ultrasounds performed during the 5th week of pregnancy.

An ultrasound shows the "double ring" sign of a gestational sac and yolk sac. This is commonly seen on ultrasounds performed during the 5th week of pregnancy.

Cramping or Bleeding at Five Weeks Pregnant

Spotting is a common concern at this stage of pregnancy. Mild pinching and pulling sensations are often normal, but severe cramping is not typical. In addition, sometimes spotting is due to "old blood" from implantation, but any bright red bleeding or spotting should be reported to a physician promptly. Approximately 50% of pregnancies that have spotting in early pregnancy go on to have healthy babies, while the other half do experience an early miscarriage.

A physician will be able to order a viability ultrasound, which can determine uterine lining thickness and determine the presence of a gestational sac at this stage of a pregnancy. Sometimes a yolk sac or fetal pole are visible, showing the presence of the embryo. The heartbeat is not typically observed until around six weeks of pregnancy, so the scan may be repeated in a week's time to monitor the baby.

In addition to an ultrasound, the doctor may order blood work to determine the concentration of beta human chorionic gonadotropin, or beta hCG. This hormone is produced in pregnancy and should double every 2-3 days. By taking blood draws over the course of a few days, the doctor can tell if the hormone levels are rising as they should, or if a miscarriage is impending.


Avoid Toxins in Early Pregnancy

Stay away from deli meats and soft cheeses: these food items may carry a bacteria called Listeria, which is extremely harmful for the embryo. Listeriosis causes miscarriage in early pregnancy and fetal death in later pregnancy. While it is not common in the United States, any exposure could be devastating and the risk is simply not worth it. Instead of ordering a sandwich with deli meat, try ordering a version with cooked meat.

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Do not smoke or drink in early pregnancy, as both can cause birth defects or intra-uterine growth retardation (IUGR), which harms the development of the baby.

Don't take any medication without consulting your physician to determine if it is safe. Drugs are classified into an alphabetical labeling system which states the known risk level to a developing baby. Class A drugs are drugs which have been studied and do not demonstrate any harm to an embryo or fetus, and Class D, Class X, and Class N drugs are known to cause harm to the developing baby.

Most doctors will allow a woman to take regular strength acetominophen (Tylenol) for headaches.

Pharmaceutical Pregnancy Categories

Drug ClassDefinitionDrug Examples


No evidence of harm or risk to the developing baby.

Folic acid


Animal studies show risk while human studies do not, OR animal studies show the drug is safe, but the drug has not been studied in human pregnancies.

Amoxicillin, acetaminophen


There are insufficient studies of the drug in pregnant humans, though animal studies show risk. Some drugs in this category may be used in pregnancy if the benefit outweighs the risk.

Theophylline, Sudafed


Harm has been demonstrated to a fetus in human pregnancies, though the drug may still be used if the benefits outweigh the risk.

Lithium, chemotherapy drugs


Birth defects and damage to the fetus have been documented and the risks do not outweigh any potential benefit.

Thalidomide, Accutane


Toxoplasmosis and Pregnancy

Toxoplasma gondii, as seen in a brain biopsy. This organism is found in soil and in cat litter, and can cause miscarriage or birth defects to a developing baby.

Toxoplasma gondii, as seen in a brain biopsy. This organism is found in soil and in cat litter, and can cause miscarriage or birth defects to a developing baby.

Preventive Health Measures for Pregnant Women

The embryo is extremely fragile at this state of development,and environmental toxins and infectious diseases may cause miscarriage or birth defects. There are a number of measures pregnant women can take to prevent exposure to many viruses and parasites:

  • Get a flu shot. Influenza, particularly the H1N1 virus, has been known to cause miscarriage.
  • Avoid changing the cat litter. Toxoplasmosis, a parasite carried by cats, is known to cause miscarriage or birth defects.
  • Do not eat soft cheeses, uncooked deli meats, and wash all fruit and vegetables before consumption. Listeria, a bacteria that lives in unpasteurized dairy products and in the soil, can cause fetal death.
  • Wash your hands frequently, particularly if you work in a daycare facility or around small children. Cytomegalovirus and Parvovirus are two viruses that are known to cause birth defects or miscarriage in pregnant women.
  • Ensure all of your vaccinations are up-to-date. Rubella is another virus that can wreak havoc on a developing baby.


Leah Lefler (author) from Western New York on February 06, 2019:

I would contact your local OB/GYN as soon as possible, Stacey, to confirm the pregnancy and to establish dates. Your OB will be able to test beta hCG levels and an ultrasound to determine approximately how far along you are. It is important to obtain regular health monitoring once you receive a positive result!

StaceyDaniels on February 01, 2019:

I can't remember when my last period was due to not keeping track of my menstrual cycle but yesterday i took the ClearBlue test and it says 3+ weeks so if there's any help please please

Leah Lefler (author) from Western New York on June 11, 2018:

I remember those weeks well, Sophia! I was lucky and by 12 weeks my nausea had mostly dissipated - I hope you are through the icky stage soon, too. Pregnancy affects everyone differently and this part can be a real challenge. I survived on Otter Pops (the frozen ice pops) for weeks with my first child as it was the only thing I could keep down!

Sophia1990 on June 07, 2018:

6 weeks in and I throw up From chicken pot pie!! Get nauseous from carrot cake, chicken nuggets, grilled cheese and tomato soup. Breasts are so sore and only feel better in a sports bra. Bloating. My feet were swollen the other day. Been craving sweets but every time I get one in me I get nauseous from it. Being pregnant is tricky right now I feel like. I have no idea what’s going to set me off and what will not.

Leah Lefler (author) from Western New York on July 23, 2014:

Joyce, I hope you have determined whether you are pregnant or not by now - one thing you can ask for is a blood test called a beta hCG test. This will determine how much pregnancy hormone (if any) is in your system. There are many reasons for a missed period, so it is important to seek medical advice if your cycles aren't typical and/or if you suspect a pregnancy.

joyce on May 30, 2014:

Gud last period was march 24.then april missed may end no menstrual period.actived in sex.but i used pregnancytest said i am pregnant? Please help.

Leah Lefler (author) from Western New York on January 21, 2014:

Ana Maple, the only way to determine if you are pregnant is to take a pregnancy test and to see a doctor to confirm any potential pregnancy.

Ana Maple on January 09, 2014:

I had my period for 1day do that mean I'm pregnant.

Leah Lefler (author) from Western New York on October 23, 2012:

The early weeks are the most exciting (and the most fragile) for the baby's development. So many things happen in the first twelve weeks! I am trying to get the rest of the hubs written - I need a time machine to get them all done quickly, lindacee!

Linda Chechar from Arizona on October 23, 2012:

Another great Hub about the stages of pregnancy. I didn't realize how critical each week was in development. I think is this a wonderful idea for a Hub series! Can't wait to read more! :)

Leah Lefler (author) from Western New York on October 23, 2012:

I love Western NY, swetypie1968! We live in Jamestown, and I love raising my boys in a place so filled with nature. Of course, the winter months are long and hard for me (I'm a Southern California native)!

Dianna Mendez on October 23, 2012:

Thanks for the information, Audra. I try to eat only the better, natural brand of deli meats now, if at all.

sweetypie1968 on October 23, 2012:

This is quite interesting. My baby making days are also long behind me, but I just wanted to say "hello" since you also live here in Western New York.

Leah Lefler (author) from Western New York on October 23, 2012:

Many cheese varieties are OK, teaches12345 - Mozzarella, cheddar, American - only the soft cheeses like Brie are potentially dangerous. The biggest danger comes from unpasteurized milk (with respect to Listeriosis), though the condition is not common. I just avoided Subway Subs and other sandwiches with deli meats until I had delivered - the risks, while rare, are devastating if the mother does ingest Listeria!

Dianna Mendez on October 22, 2012:

Even though I am past this stage of life, I find reading this so educational and fascinating. I am sure many women are benefiting from this read. I had a miscarriage in my twenties and I wonder if some of the tips you posted had anything to do with it. I loved cheese back then and deli meats. Can't second guess it now, but it's really something to think about for future moms. Voted way up!

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