1 Week Pregnant: What’s Happening Inside Your Body?

Fact Checked Medically reviewed by Tanja Premru-Sršen


Every week counts for the woman trying to conceive and get pregnant! The first week of your pregnancy is technically not the first week of pregnancy, but the week of your last menstrual period (lmp).

The due date is calculated as forty weeks from the first day of your last menstrual period, which means that the birth countdown actually begins about two weeks before the child has even been conceived, right around that month’s menstrual period.

However, every healthy pregnancy starts before the woman becomes physically pregnant, by parents mentally and physically preparing themselves for a baby, especially future moms.

While counting the days of your menstrual cycle and anticipating the pregnancy journey at 1 week pregnant, you can work on getting and staying healthy for your little bundle of joy that is going to join you soon. Here is how.

What to expect during the first week of the menstrual period?

You can expect some things during your first week of pregnancy and menstrual cycle, even though you are not technically pregnant.

Early pregnancy symptoms during week one of pregnancy and menstrual cycle

At such an early stage of the journey, the early signs you are going to be experiencing are the typical menstrual symptoms of your menstrual period, which is why they might look oddly familiar once you read them.

Chances are, you have experienced these pregnancy-like symptoms hundreds of times before. However, this is special since you are trying to conceive a healthy pregnancy, so it is important to carefully note and track these pregnancy symptoms for your healthcare providers in the future.

These symptoms can last from three to seven days, and they most commonly include:

Vaginal bleeding

During this week, your body is going to be shedding the uterine lining, which was plumped up just in case of a possible pregnancy. This is just a normal period, just like any other month, and there is no need to be concerned about it.

Mood swings

Thanks to the intense hormone surges that you are going through during this week, you are very likely to experience irritability that is going to wreak havoc on your emotions, as well as other early pregnancy-like symptoms.


Many women complain that they experience menstrual migraines, which are also hormone-related. Just like mood swings, headaches tend to appear thanks to surges in hormones. If you happen to struggle with this uncomfortable symptom, ice packs, pain relievers, and relaxation exercises might be your best friend that is going to help you get rid of that pain.

Lower back pain and cramps

Your body has to make your uterus contract in order to release the uterine lining. These contractions can cause your stomach and your back to hurt and feel uncomfortable.

Bloating and breast tenderness

Apart from giving you mood swings, headaches, and cramps, fluctuating hormones can also give you a bloated belly during your period, as well as tender breasts.

What happens to the baby inside during week one?

As previously mentioned, you will not be pregnant during week one. While there is not a baby growing just yet, your body is still getting ready for pregnancy. During this week, your body releases last month’s uterine lining and starts to form a new one, which will hold next month’s fertilized egg, with a bit of luck on your side.

After three to seven days after the start of your menstrual period, your ovaries will start to prepare this month’s egg. This little egg will be released during ovulation, and the lining of the uterus begins to thicken to accept that egg after it has been fertilized. If all goes well, conception can be expected around week three.

Pregnancy Checklist

Even though you are not pregnant during this week, there are still some things that you should do to prepare your body for the baby that you are hoping for. If you are actively trying to conceive, make sure to:

  • Evaluate your nutrition, and make sure your diet is full of healthy and filling foods that will nourish your body.
  • Quit smoking.
  • Stop drinking alcohol.
  • Avoid greasy, heavy, salty foods that will make you feel bloated and uncomfortable.
  • Limit your excessive caffeine intake.
  • If not before, start taking 400 mcg folic acid per day.
  • If you are a vegetarian or have a limited sun exposure, start taking 1000 – 2000 IU vitamin D per day.
  • Start taking prenatal vitamins daily, if you have a special diet from which certain foods are excluded.
  • If you have not been doing this before, your first week is the perfect time to track your cycle to pinpoint your most fertile days.