It produces the important hormones, estrogen and progesterone. Progesterone relaxes the muscular wall of the uterus and prepares its tissue lining so that the embryo can implant. Estrogen is key for the development of the foetus, stimulating organ growth and thickening the lining of the uterus. For the first few days after conception, its levels can be too low to be detected by pregnancy tests.
After implantation its levels double approximately every 48 hours, making it much easier to detect. Urine is applied to a sample pad at the end of the test stick and is drawn up the strip. The first area it reaches is the reaction zone. If hCG is present in the urine, here it binds to proteins called antibodies.
These antibodies have an enzyme attached to them which can participate in reactions further along the test strip.
The test zone contains different antibodies which are attached to the strip and unable to move. These antibodies also bind to hCG, creating something of a hCG sandwich between the two different antibodies.
The enzyme on the mobile antibodies triggers a colour change in dye molecules on the test strip. A positive home pregnancy test simply means that HCG is present in the urine, while a negative test can have a variety of meanings. Negative tests can mean that there is no pregnancy, or they can mean that the test was either taken too early to detect HCG, or that it was not done correctly.
If the result is positive, the woman should make an appointment to see a healthcare professional, who can guide her about the next steps. If the result is negative, but the woman has the signs and symptoms of pregnancy, she should test again after 1 week or ask a doctor about a blood test instead. Some modern pregnancy tests and kits can give an estimate of the conception date and consequent due date.
However, this information is not always accurate. These include :. Alcohol in the blood stream does not affect the pregnancy test because it does not interfere with the measurement of the hormone levels. However, anyone who is trying to or expecting to become pregnant should avoid alcohol , as it can affect fetal development. Drinking during early pregnancy can increase the risk of miscarriage, premature birth, and low birth weight. Sometimes, there may be a positive test result but the woman is not pregnant.
High HCG can also indicate that some health condition has increased levels of the hormone. HCG can rise as a result of some types of cancer. These are transitional cell carcinoma of the bladder and urinary tract, prostate cancer , renal cancer, and cancers of the gastrointestinal system.
A pregnancy test may be used to assess for these. Pregnancy tests are available at drugstores, pharmacies, and some convenience stores. Home pregnancy tests can be purchased for as little as a dollar, and some health centers offer them free of charge. Learn more. Fetal macrosomia is a condition wherein a baby is born at a heavier birth weight than usual. Learn more about fetal macrosomia here. A study links air pollution to almost 6 million premature births each year. Indoor air pollution is responsible for two-thirds of these perinatal….
Amniotic fluid embolism is a dangerous pregnancy complication that develops due to a severe allergic reaction. If you're not sure about continuing with the pregnancy, you can discuss this confidentially with a healthcare professional.
Your options are:. As well as a GP or a nurse at your GP surgery, you can also get accurate, confidential information — from the age of 13 — from the following:. All these services — including community contraceptive clinics — are confidential. If you're 13 or older, the staff won't tell your parents. They'll encourage you to talk to your parents, but they won't force you.
If you're under 25 and would prefer advice specifically for young people, the sexual health charity Brook provides a range of services for young people. The Brook website contains information on pregnancy choices. Take our survey. Page last reviewed: 1 October Next review due: 1 October Home Pregnancy Trying for a baby Back to Trying for a baby.
Doing a pregnancy test. When you can do a pregnancy test You can carry out most pregnancy tests from the first day of a missed period. Where you can get a pregnancy test You can also buy pregnancy testing kits from pharmacists and some supermarkets.
The following places provide free pregnancy tests: community contraceptive clinics — find sexual health services near you sexual health clinics some young people's services — call the national sexual health helpline on for details Brook centres — for unders You may also be able to get a pregnancy test free of charge from your GP.
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