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Week 1 of Pregnancy: All You Need to Know

Baby Development|Body & Life Changes|Your Doctor Visits|Health & Safety
Week 1 of Pregnancy: All You Need to Know

Baby Development

How is my baby growing?

The first week of pregnancy can be a bit confusing. Usually, by the time you find out you are pregnant, you are already at least 4 weeks into your pregnancy. It is hard to know the exact date of when your egg becomes fertilized but the start of your menstrual cycle is very clear. For this reason, doctors calculate your due date by using the first day of your last menstrual period (LMP). Still confused? Don’t worry. All you need to know is that the first 2 weeks are considered to allow your doctor to make the best estimation of your due date. Your pregnancy will usually last for 40 weeks but some babies may be ready for birth at 38 weeks, while others could wait up until 42 weeks. However, your doctor will not allow it to run any longer than 42 weeks. Now that we shed some light on how your due date is calculated, let’s see how your body is changing.

Body & Life Changes

How is my body changing?

During this time, your body is preparing for ovulation. Ovulation occurs when an egg is released from your ovary, a process that usually takes place between 12 to 14 days after the first day of your period. There are hormones circulating in your body to prepare for your egg to be fertilized. You may feel that your breasts become swollen and tender. You may also experience some abdominal cramps. These are all common signs and symptoms of your menstrual period. At this point, you should already be prepared for egg fertilization to take place in about 2 weeks’ time. Mark your calendars and be sure to inform your partner about the good news.

What should I be concerned about?

During this week, you need not be worried about anything. The only thing you should focus on is maintaining a healthy diet and taking prenatal vitamins consistently. It is important to consume adequate amounts of vitamins, especially folic acid during this crucial stage. Folic acid is needed to reduce the risk of neural tube defects (birth defects caused by incomplete development of the brain or spinal cord), such as spina bifida. The recommended dose at this stage is about 400 micrograms of folic acid per day. The dose may be higher for women who have a history of spina bifida.

Your Doctor Visits

What should I tell my doctor?

It is important for you to tell your doctor what prescription drugs, nonprescription (OTC) drugs, or herbal supplements you are currently taking. This is because these drugs may potentially cause harm to your baby. If there are any prescription drugs that you need to take regularly, you should not stop taking them without consulting your doctor first. Your doctor will need to weigh out the potential benefits and risks of halting your medications.

Questions to ask your doctor:

  • Can I keep taking my prescription and over-the-counter medication while pregnant?
  • What should I do before getting pregnant?
  • Are there any vaccinations I need before getting pregnant?

What tests should I know about?

To prepare your body for your baby, your doctor will perform an overall examination. Your doctor may request to conduct the following tests:

  • Pap smear, which will help detect any anomalies that could affect your chances of conceiving.
  • Genetic tests, which will help detect possible genetic diseases that may be passed down to your baby through inheritance. Such diseases include sickle cell anemia, thalassemia, and Tay-Sachs disease.
  • Blood tests, which will detect any sexually transmitted diseases (STDs) or immunity to rubella and chickenpox. This will determine if you require any treatment or vaccinations before getting pregnant.

These tests will help your doctor give you precise guidance to prepare your body for a healthy baby.

Health & Safety

What should I know about being healthy and safe while pregnant?

You are probably wondering about what you need to avoid to ensure a healthy pregnancy. When you are pregnant, your immune system will not be as strong as before, therefore you are more likely to be susceptible to infections. You may want to talk to your doctor about vaccinations that are safe for you. Here are some vaccines you may want to consider or avoid indefinitely:

Measles Mumps and Rubella (MMR) vaccine

Measles is a viral infection. Some signs and symptoms include mild fever, cough, runny nose which are followed by spotted red rash after a couple of days. Mumps is also a contagious viral infection that causes the salivary glands to swell. If you are infected with either one during pregnancy, the risk of miscarriage is high. The rubella virus, also called German measles, presents flu-like symptoms which are often followed by a rash. Up to 85% of babies of mothers who contract it during the first trimester tend to develop serious birth defects, such as hearing loss and intellectual disabilities. This vaccine clearly is not safe to take during pregnancy. You would typically need to wait for 1 to 3 months after receiving the MMR vaccine before getting pregnant. Please consult with a doctor for a more accurate gauge of the matter.

Chickenpox vaccine

Chickenpox is an extremely contagious viral disease that causes fever and an uncomfortable, itchy rash. About 2% of babies of mothers who develop chickenpox during the first five months of pregnancy might have birth defects, including malformed and paralyzed limbs. A mother who develops chickenpox around the time of delivery can also pass down a life-threatening form of the infection to her baby. This vaccine is considered not safe during pregnancy, and therefore it is best to consult with your doctor before getting pregnant.

Flu shot

It is recommended by the Centers for Disease Control and Prevention (CDC) to get the flu shot when you are pregnant. The flu shot is made of dead viruses and will not harm your baby. You should avoid a nasal spray flu vaccine called FluMist, which is made of live viruses.

If you contract any type of flu while being pregnant, you are more likely to develop serious complications. This includes pneumonia, which is potentially life-threatening and may also increase your risk for preterm labor. You are also at risk for flu-related complications during the postpartum period.

The flu vaccine is usually safe during pregnancy. There is evidence to prove that getting a flu shot during pregnancy will guarantee your baby some protection after birth. Your baby may also receive some antibodies from you during pregnancy. If you are immune to these complications, your newborn is less likely to be exposed to the flu.

Let’s explore the following week of pregnancy in the next article.

Hello Health Group does not offer any advice, diagnosis, or medical treatment.


Due Date Calculator

Use this calculator to find your due date. This is just an estimate – not a guarantee! Most women, but not all, will deliver their babies within a week before or after this date range.

Cycle Length

28 days

Hello Health Group does not provide medical advice, diagnosis or treatment.

Your baby at weeks 1 and 2 http://www.whattoexpect.com/pregnancy/week-by-week/weeks-1-and-2.aspx. Accessed May 27, 2016. Pregnancy Calendar - Week 1 http://kidshealth.org/parent/pregnancy_center/pregnancy_calendar/week1.html. Accessed May 27, 2016. How to calculate your due date. http://www.whattoexpect.com/pregnancy/pregnancy-health/calculating-due-date.aspx. Accessed May 27, 2016.
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Written by Kristel Dacumos-Lagorza Updated Jun 30, 2021
Medically reviewed by Jobelle Ann Dela Cruz Bigalbal, M.D.