For a woman of childbearing age, the “Fertile Window” is one week during every cycle when sex can result in pregnancy.  It starts a little before the  release of an egg from the ovary and lasts up to a week, covering the time when the viable egg is traveling to the womb.  If unprotected sex occurs and sperm encounter the egg on its journey, the egg can be fertilized. 

The fertilization of an ovum, or egg, by a sperm results in changes in a woman’s menstrual cycle, causing her period to be “late.”  This late period may be the first sign that the woman is pregnant.  This happens around the six week mark from the last period and is the earliest point where the pregnancy can be confirmed.  It is often referred to as the six week pregnancy.  Other signs and symptoms of pregnancy soon follow, but it is her late period that most often causes the woman to suspect that she is pregnant.   

Here is an example to help you understand dates and your fertility with an emphasis on the potential for pregnancy following unprotected sex.  These dates are examples or estimates, they are not precise.

• First day of last normal menstrual period:  August 2
• Dates of the last menstrual period:   August 2- 8
• Approximate ovulation:  August 15 (two weeks after the start of the last period)
• Fertile days:  August 13-19
• Earliest date to see HCG in the urine:  August 27-29
• Expected first day of the next normal menstrual period:  August 29
• First concern for suspected pregnancy:  September 5

The fertile days are from a short period before ovulation and up to a few days after.  Once the sperm are in the reproductive tract, they can survive up to three (3) days awaiting the release of the egg and the egg is viable for a few days after its release.  Generally, the egg is fertilized within 12 – 24 hours after release.

If pregnancy does not occur the expected onset of the next period of a 28-day cycle would be August 29.  

Using this example once the anticipated period does not occur, there is a six week pregnancy.  

Pregnancy Signs and Symptoms at Six Weeks

• Missed period
• Metallic taste in mouth
• Tender breasts
• Nausea
• Increased urination
• Fatigue
• Mood swings
• Some food cravings
• Constipation
• Light spotting
• Tender Breasts: Hormonal changes might make your breasts sensitive and sore.  The tenderness and discomfort typically decreases after a few weeks.
• Nausea With or Without Vomiting; “Morning Sickness”: Morning sickness can strike at any time of the day or night.  It often begins about one month after the egg is fertilized.  The experience of nausea varies from woman to woman, some get it very early and some never get it. Your partner might be observing you out of concern to see if you are able to keep your food down.  
• Increased urination: During pregnancy the woman’s total blood volume increases so the kidneys work harder and produce more urine than during the non-pregnant state.  Late in the pregnancy there is pressure on the bladder and one feels the need to empty it frequently.  
• Fatigue: Progesterone is a hormone produced and released by the ovaries.  Progesterone is necessary for implantation of the fertilized egg into the uterine wall in the womb and for maintaining pregnancy.  Fatigue is a side effect of progesterone.

Six Week Pregnancy Papers – HCG

Urine pregnancy tests typically measure the amount of Human Chorionic Gonadotropin (HCG) in the urine.  This “pregnancy hormone” is made by cells in the placenta and can be detected in the urine 12 – 14 days after conception.  The level of HCG typically doubles every 72 hours. Urine pregnancy tests that are “Qualitative for HCG”  show HCG is present in the urine sample.  The tests that are “Quantitative for HCG”  measure the amount of HCG in the urine sample.

At 6 weeks gestation the amount of HCG expected to be present in urine is: 1080 – 56500 mIU/ml.

The Fake Pregnancy Papers provided by Babymaybeshop.com can be customized to show a level of HCG that is consistent with the expected range at 6 weeks gestation.

6 Week Ultrasounds

Why get an ultrasound at 6 weeks gestation?

• To confirm a pregnancy with a test that is more accurate than a urine HCG pregnancy test, and
• To establish gestational (how long since fertilized) age, and  
• To confirm the presence of an intrauterine pregnancy.

What will you likely see in a 6-week ultrasound?

• An embryo that is about 2mm in size.
  • The embryo looks like a tiny white curled object that is surrounded by the yolk sac.  
• The yolk sac looks like a small white circle on the ultrasound.
  • The yolk sac nourishes the embryo and helps produce blood cells during the early stages of pregnancy.
• The gestational sac, presenting as a large black area, surrounds the yolk sac.
  • The gestational sac contains amniotic fluid.
  • On the ultrasound, the gestational sac is seen as early as 4 ½ to 6 weeks.   

If you are fortunate, you may get to see the flicker of a tiny heartbeat as early as your first ultrasound at the six week pregnancy!  But, don’t worry, if the sonographer conducting the test cannot show it to you or see it.  While it is really exciting to see the beating of the heart, it is more common for the heartbeat to be seen at 6 weeks or later.   

What if nothing shows up on the ultrasound?

Patience is key during pregnancy. Some women may go in for an ultrasound of the six week pregnancy only to hear that the gestational sac isn’t showing up yet.  There are a number of reasons for the absence of the yolk sac.   

It’s too early

You may have counted the days incorrectly if the gestational sac is not seen.  If you are not at the six week pregnancy stage or later, you may not see the sac.  

The presence or absence of the sac and related tissues, the size and structure of the sac, and the location of the sac are all useful in dating the pregnancy.

Ectopic pregnancy

An ectopic pregnancy happens when a fertilized egg implants and grows outside the main cavity of the uterus.

An ectopic pregnancy is a medical emergency!  An ectopic pregnancy requires treatment and may cause bleeding inside the abdomen, vaginal bleeding, or pelvic pain.  

An ectopic pregnancy would not show any signs of an intrauterine pregnancy since most occur in a fallopian tube.  Sometimes the fertilized egg falls out of the tube into the abdominal cavity where it can connect to other kinds of tissue. Though rare, some embryos are able to survive for a period of time outside of the uterus. When this occurs it is a medical emergency.  

This is a less common finding than “wrong dates.”

Miscarriage

A miscarriage happens when a fertilized egg does not properly form an embryo or implant in the lining of the uterus properly causing the fertilized egg and related tissues to be lost.      

Vaginal bleeding after a pregnancy has been established and documented may be a medical emergency!  See your doctor if you have questions or concerns about vaginal bleeding or miscarriage.

Inability to find a gestational sac on the ultrasound and HCG levels that are lower than those on the last exam point to the possibility of an early miscarriage.

Vaginal bleeding is a common sign of a miscarriage but is not unique to miscarriage — vaginal bleeding may mean something else in your pregnancy.

This information is presented to be a general guide to the events surrounding a normal uterine six week pregnancy, the time when you may first become aware of your condition.  It is for informational purposes only.  The information provided is not intended to be the only information available concerning early pregnancy or expected to be a substitute for professional guidance or the advice of your physician or health care provider. 

If you have any questions, concerns, apprehensions, unease, or worry about your fetus’ development contact your health care provider immediately.