Blood Testing for Sexually Transmitted Infections during Pregnancy

It surprises many people to find that some of the routine tests performed during pregnancy are for sexually transmitted infections. Antenatal care across the UK will involve testing pregnant women for conditions like syphilis, gonorrhea, and chlamydia, and many will also suggest testing the father to be for these diseases as well in case of a false or inaccurate result.

Why are sexually transmitted diseases tested for during pregnancy?

STIs are a particular concerns for pregnant women because of the serious health risks these conditions can pose to newborn babies. A baby can be exposed to a condition either through the exchange of blood between mother and child at the placenta, or more commonly during his or her passage through the birth canal during childbirth. Many STIs are caused by bacteria which reside in the vagina or birth canal, and as a child is being born he or she is naturally exposed to these parts of the anatomy and thereby get infected.


STIs can often be far more severe in newborns, and some conditions like Gonorrhea can be life threatening in infants. Newborn babies are far more vulnerable to infectious agents as their immune systems (the body’s innate defense mechanisms) are not very well developed. This is one of the major reasons for testing pregnant women for any signs of these potentially dangerous illnesses.

STIs are also tested for because many, particularly extremely common ones like Gonorrhea and Chlamydia, often do not present with any observable symptoms. What this means is that a pregnant woman can be asymptomatic during her pregnancy, and so any STIs that don’t have symptoms won’t be diagnosed.

Blood testing for STIs during pregnancy

As discussed so far in this article, there are many important medical reasons that drive the testing of pregnant mothers for signs of sexually transmitted diseases. One of the important methods of determining whether or not a mother is carrying an STI is through blood testing.

Blood tests are used for their accuracy and reliability, and also because blood samples are taken for a variety of other tests during pregnancy making this technique convenient as well. Blood tests can be used to either check for the presence of STI causing infectious agents directly, or to monitor your body’s defense mechanisms which can indicate certain diseases. The latter works by what is called antibody testing, a technique which examines a product of your body’s immune system, antibodies, to determine which, if any, infections you bear.

Is blood testing safe during pregnancy?            

Understandably the safety of blood tests during pregnancy is a major concern for both parents to be and their doctors or midwives. Fortunately blood tests are an extremely safe and effective method of testing for STIs as well as a wealth of other conditions. A small amount of blood is needed for the actual test itself, and only enough is extracted to allow for accurate and reliable testing. This amount of blood is easily replaced by your body with no adverse effects for you or your child.

Where can I get blood tests for STIs during pregnancy?

Blood testing for sexually transmitted infections is now a routine part of antenatal care, and as such your care provider, be they private or on the NHS, will provide you with a blood screen for STIs.

After your test you might have to wait for a few weeks for the results to get back to you. If your test comes back positive for an STI then you will receive the treatment you need to get rid of the condition and thereby have a safe pregnancy and delivery. There are some conditions however, which can’t be treated, and the most prominent example of these are HIV (the virus causing AIDS) and Herpes. In the event of either of these infections alternative methods are chosen to try and make your delivery as safe as possible and prevent the exposure of your newborn to these STIs.


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