Pregnancy Week 1
Your First Week of Pregnancy
& Stage of Fetal Development

Week 1 begins with your menstrual period.  Your body is preparing for another round of your ovulation cycle by finishing up your last cycle by flushing out the contents of your uterus to begin anew.

When counting the 40 weeks of pregnancy, the first week starts with the first day of your last menstrual period. This means that you are not actually pregnant yet (see pregnancy chart).

If you would like information on the first week of actual pregnancy (first week of fetal development), which generally occurs at the end of week 3 of the 40 weeks of pregnancy after ovulation, see 3 weeks pregnant: conception occurs or 4 weeks pregnant: implantation occurs. Also see When does conception occur? and When does implantation occur?.

During your previous cycle, your body was preparing for a pregnancy by thickening your endometrium (the lining of the uterus) to accept the implantation of a fertilized egg. Since you are on your period, implantation obviously did not occur.

So now you start a fresh new cycle in the hopes of becoming pregnant. Pregnancy week 1 begins this new cycle by allowing your body to start with a fresh new lining that will thicken and develop in order to accept a newly fertilized egg. Once the embryo is implanted, then you are considered officially pregnant.

By the end of week one, your menstruation will have stopped, and the beginnings of a new lining will begin to evolve.

What is happening during pregnancy week 1

Lots of things are occurring during your first week of pregnancy. The start of week 1 is the start of the follicular phase and the first day of your ovulation cycle (Cycle Day 1 or CD1).

FSH (follicle stimulating hormone) is rising. FSH stimulates your ovaries to grow follicles which each contain an egg. During this phase, you will have many eggs growing in anticipation of being the one from the dominant ovarian follicle to be expelled from the ovary at ovulation.

During this first week, estrogen will also begin to rise. Estradiol (a form of estrogen) is being mostly produced from the growing follicles in your ovaries. Estrogen begins the process of thickening your uterine lining. Building it up so it's able to accept the growing embryo.

As estrogen levels get higher, your FSH levels will begin to taper off signaling that enough eggs have been stimulated to grow and are not needed at this time. Your estrogen levels will continue to rise into the second week of pregnancy further thickening your lining.

Progesterone levels will be at there lowest at the beginning of the first week of pregnancy (the start of your period). The decline of the production of progesterone during your previous cycle is what caused your period to start. Progesterone is dominant in the luteal phase of your cycle and is what will further prepare your endometrium for implantation which occurs during week 3 and week 4.

What can you do during pregnancy week 1

This is a great time (if you haven't already) to begin to eat a healthy, nourishing fertility diet or pregnancy diet. I can never stress enough how important proper nutrition is to ensuring a healthy pregnancy and healthy baby.

You may also wish to start taking fertility vitamins and supplements and/or prenatal vitamins to ensure you are getting all the nutrition you need.

During the first week of pregnancy, you may want to start charting your basal body temperature (BBT) and other signs of ovulation. This will help you to determine when ovulation occurs and when to have intercourse. See also getting pregnant positions.

Also, you may want to get an ovulation predictor kit. You will start to test with the ovulation sticks during week 2 as ovulation gets closer.

For those of you who have been trying for awhile, you may want to invest in a fertility monitor. These are little computers that help you to determine when you are about to ovulate so you can better prepare. Or even for those that just want an easier way to predict when to have baby making sex rather that peeing on a stick or checking your cervix for fertile quality cervical mucus.

You may want to get a journal to keep track of all your pregnant moments to remember later. A journal is a great way to keep track of your weight gain, photos of your growing belly, your feelings during each stage of your pregnancy, and so on.

It's also great at helping to relieve stress so you have a healthy pregnancy and baby as the anticipation of becoming pregnant and growing a new life can sometime be overwhelming.

Expecting a Miracle Journal is a guided pregnancy journal for the new mom-to-be.

Remember to take a picture of your week-one belly.

You can also check out this page on how to increase fertility naturally and relieve stress.

Speaking of natural, one of the best ways to have a naturally healthy pregnancy, labor & delivery, and baby is to pick up some red raspberry leaf tea. Drink 3 cups a day now while TTC.

This natural herbal "pregnancy" tea will help relieve PMS, menstrual cramps, and help prevent pregnancy symptoms like morning sickness and constipation. It also helps prepare your uterus for pregnancy and helps ease labor & delivery.

It's full of vitamins, minerals, and other nutrients for the health of you and your baby.

And don't forget about preconception care and pregnancy planning.

Fetal Development in pregnancy week 1

During the first week of pregnancy, your future baby is a single cell inside an ovarian follicle which is about 5 mm. The egg itself is much smaller. Your egg is about 0.1 mm which is about the size of a speck of dust and can barely, if at all, be seen with the naked eye in this early tertiary stage of pre-ovulatory development.

Pregnancy week 1- follicular phase- fetal development- tertiary follicle and primary oocyte Early Tertiary Follicle and Primary Oocyte
Fetal Development
Pregnancy Week 1

Your future baby (at this stage is a primary oocyte) is competing with several other follicles (eggs/oocytes) during pregnancy week 1 to be the one to get ovulated.

Under the influence of FSH (which is at it's highest levels now in the 1st week of pregnancy), the eggs and follicles will continue to grow and begin to secrete estrogen.

The estrogen produced will slow down the production of FSH. Estrogen will also begin to change your cervical mucus to create a more receptive environment for the sperm to travel to the egg just before ovulation. It also, among other things, will proliferate (build up) your uterine lining to be able to accept the fertilized egg during implantation.

Deciding to become pregnant is very exciting and you're in for a lot of changes. Changes in your body, in your mood, and in your life.

Here's to a happy and healthy nine months!!

1 Week ››


Find this page helpful/informative?  Please "Like" it and leave me a Comment below!