One Week Pregnant: Symptoms, Baby Development & Tips To Follow

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The first symptom of your pregnancy is considered to be your missed period. Along with that, there are other symptoms of pregnancy in the first month that you might experience. Your body begins to prepare for the baby, and there are many hormonal changes taking place as well.

But an interesting fact that you should note is that you are not pregnant in the first two weeks of your pregnancy. So why are the two weeks counted in the gestation period? Read on to understand more about this and other changes that are happening in your body during this period.

The First Week Of Pregnancy

Most women might not know they are pregnant in the first week. However, if you have been planning to get pregnant, you must be tracking your menstrual cycle diligently. In such a case, you may be able to figure out or guess the first week of pregnancy. Let’s see how to calculate it.

The calculation of 40 weeks starts from the first day of your last period – this calculation is used to determine what is called the gestational age. That means you are actually on your period in the first week. Two weeks after that, or around day 14, you start ovulating, which is why the early symptoms of pregnancy and your period symptoms are similar.

After five or six days of ovulation, implantation occurs, which means the fertilized egg is implanted on to the uterus lining. This is the time when you technically become pregnant (1). The first two weeks is when your body is preparing for the pregnancy, which is why they are considered a part of the 40-week pregnancy period.

Fetal Development In the First Week Of Pregnancy

There is no sign of the baby at such an early stage of pregnancy as this is the time when your body is preparing for ovulation. However, the first stage of its development starts in the coming weeks when the mature egg is fertilized by the sperm and forms the zygote, which is the first cell. Then cell division results in blastocyst or ball of cells (2).

Then there is the division of cells, after which the fertilized egg is implanted on to the uterine wall. This is the beginning of the baby’s development in the womb.

Continue reading to know what happens to your body in the first pregnancy week.

Body Changes During The First Week Of Pregnancy

In the first week of pregnancy, you will be on your periods. So you may not know your pregnancy has begun. During this time, your body sheds the previous month’s eggs and uterine lining. After the first week, new and mature eggs will be released, and the uterine lining begins to thicken again.

The symptoms of the first-week pregnancy are pretty much similar to those you experience before and during periods, which we see in the next section.

What Are The First Week Pregnancy Symptoms?

You may experience the following symptoms during the first week of pregnancy (3).

  1. As the hormonal fluctuation is severe this time, you may experience bloating and discomfort during the first week.
  1. You may feel extremely tired even if you are doing nothing. That could be because your body is preparing for pregnancy.
  1. You may notice swollen and tender breasts around this week due to hormonal changes in the body. You may crave for salty or sweet foods during the first week. Food cravings and aversions are likely to happen, and they increase in the coming weeks.
  1. Headache, cramps, and pain in the lower back are some other common symptoms that you may experience in the first week. However, if they become severe, call your doctor.

Read on for a few tips on how to take care of yourself in the first week of pregnancy.

Tips For First Week Of Pregnancy

Chances are you won’t know when the first week of pregnancy is. So if you are planning to become pregnant, it is essential that you start maintaining a healthy lifestyle right away. Here are a few things to keep in mind to stay healthy in the first week and improve your chances of pregnancy (4).

  1. If you are a smoker, stop smoking right from the time you decide to conceive. Also, avoid the consumption of alcohol.
  1. Maintain an active lifestyle by eating healthy foods and exercising. Your body needs to be healthy and fit to carry the baby.
  1. You may ask your doctor about prenatal vitamins and start taking them to increase the chances of getting pregnant.
  1. Make sure you are sleeping well; this is important to stay mentally and physically active.
  1. If you have been planning to have a baby, keep track of your menstrual cycle. You can use ovulation calendars and apps to make your job easier.

If you need more guidance at this stage, you may talk to your doctor.

What Can You Ask Your Doctor?

When you and your partner plan to have a baby, talk to your doctor. Clear all your doubts, such as a change in diet, use of prenatal vitamins, tracking the ovulation cycle, and more. Get as much information as you need for a successful conception.

The first week of pregnancy can be tricky since you are not technically pregnant, and the baby hasn’t started developing yet. Further, since the symptoms of the first week of pregnancy, such as bloating, cramps, and swollen breasts, are common before menstruation, you may not know that you are pregnant. Therefore, it is recommended that you take the necessary steps right when you begin planning your pregnancy. Further, consult your ob/gyn to understand the measures you should take and the dietary changes required to ensure a healthy start to your pregnancy journey.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
  1. You and your pregnancy at 1 to 3 weeks; NHS
  2. Week 1; Embryology University of New South Wales
  3. Early Signs of Pregnancy; American Pregnancy Association
  4. First trimester; Pregnancy Birth and Baby
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Dr. Christian Pope

Dr. Christian Pope is Board-certified in Obstetrics & Gynecology, and a Fellow of the American Academy of Obstetricians and Gynecologists. He is a long-standing medical staff member and past chairman of Obstetrics and Gynecology at St. Luke's Hospital of SouthCoast Hospitals in New Bedford, Massachusetts and is in private group practice at Hawthorn Medical Associates, Inc. He is a member... more

shreeja pillai

Shreeja holds a postgraduate degree in Chemistry and diploma in Drug Regulatory Affairs. Before joining MomJunction, she worked as a research analyst with a leading multinational pharmaceutical company. Her interest in the field of medical research has developed her passion for writing research-based articles. As a writer, she aims at providing informative articles on health and pharma, especially related to... more