0 to 13 weeks
Complete Blood Count (CBC) and Anemia
A Complete Blood Count assesses all components of your blood (red blood cells, white blood cells and platelets which are involved in clotting.) An abnormally high or low count could indicate the presence of various diseases.
In pregnancy, your haemoglobin (red blood cell count) levels will be checked to make sure your blood can carry enough iron and oxygen. Because of the normal changes in pregnancy, it is very common for your haemoglobin to go down. Women experience a 50% increase in their blood volume during pregnancy but only a 30% increase in the number of red blood cells. As a result, most women will develop what we call physiologic anemia. Anemia can be especially troubling in pregnancy because a woman needs enough red blood cells to carry oxygen around her body and to her baby; if your haemoglobin is low, you could feel tired, weak and dizzy - above and beyond normal pregnancy symptoms.
Depending on your haemoglobin levels, your health care provider may suggest taking an iron supplement such as ferrous gluconate; 300 mg once a day with a glass of orange juice (Vitamin C helps absorb the iron) is usually recommended. Foods high in iron will also help with your haemoglobin levels, these include: lean red meats, seafood, egg yolks, beans and lentils, tofu, broccoli, swiss chard and, of course, spinach - all of which should be part of a balanced healthy diet.
It is important to know your blood type (A,O, B, or AB) and whether you are Rh+ or Rh-. About 15% of people are Rh- which means you could develop antibodies against the baby’s red blood cells if the baby is born Rh+. Previously, this was a major cause of stillborn deaths but we can now prevent the majority of Rh- women becoming sensitized to their baby’s red blood cells by giving Rh- mothers an injection of WinRho (or RHoGam). This absorbs any of the baby’s red blood cells that may get into the mother’s blood.
If you are Rh-, you will receive an injection of WinRho around 28 weeks and again after delivery if your baby is Rh+ (all babies have blood taken from their umbilical cord to check their blood type). You may also receive injections of Win Rho at other times during your pregnancy if there is a risk that some of your baby’s red blood cells have gotten into your bloodstream – for example: if you have a miscarriage, a pregnancy termination, chorionic villus sampling or amniocentesis, trauma or any significant bleeding episodes during pregnancy. Win Rho is a blood product that is considered safe during pregnancy.
For more information please watch the video below about Rh Factor. This video was developed by medical students at Queen's University in collaboration with faculty in the Department of Obstetrics and Gynecology.
If you haven’t had a pap smear done in the last year, one will be taken at your first appointment as part of your physical exam. A pap smear is safe during pregnancy and there is no evidence to suggest it can cause a miscarriage.
HIV/AIDS, STI’s and other viruses
Blood will be taken to determine if you are HIV positive or negative. It is important to know whether you carry HIV, the virus that causes AIDS; there are treatments now that can help prevent the virus being transmitted to your baby.
You will also have blood work done to screen for sexually transmitted infections (STI’s) such as Hepatitis B, Syphilis, and Herpes Simplex (HSV). During your PAP smear, you will be swabbed for Chlamydia and gonorrhea. It is very important to treat these infections early; if a baby were to be exposed to them at delivery there could be serious complications.
Other viruses you may be screened for which can be potentially harmful to you and your baby include: toxoplasmosis, CMV, chicken pox, parvovirus (5th disease) and Rubella (German measles).
First trimester screening (FTS) for Down Syndrome, Trisomy 18, or Spina Bifida involves a blood test done between 11-14 weeks in conjunction with a Nuchal Translucency (NT) ultrasound. This ultrasound measures the fluid-filled space at the back of every baby’s neck; Down’s syndrome can be indicated when the NT measurement is larger than expected.
If you choose Integrated Prenatal Screening (IPS) a second blood test will be done between 15-20 weeks. These tests are not definitive, but will tell you whether the chances of your baby being born with any of these abnormalities is higher than usual. Depending on the results, your health care provider may suggest further testing such as Chorionic Villus Sampling (an earlier option for women who choose FTS) or Amniocentesis (available for women who choose FTS or IPS). You may also be referred for genetic counselling based on either your screening result, a finding on your ultrasound, or an other identified risk factor.
For more information on these early screening options, visit the Prenatal Screening Ontario
Do I have to screen my baby for Down’s syndrome?
Every woman, young or old, has a chance of having a baby with either a chromosomal abnormality (such as Down Syndrome) or an anatomic abnormality (such as Spina Bifida). In fact, about 4% of all babies born have some sort of major or minor abnormality. As you get older, your risk of having a baby with a chromosomal abnormality increases.
While your health care provider will discuss the various options for prenatal screening with you, it is completely up to you to decide what you would like to do. What you do with the test results (for example, undergo further tests, terminate or continue the pregnancy) is also completely up to you. I strongly believe that knowledge is a good thing, even if you would never consider terminating a pregnancy, I still counsel my patients about their options, including further testing like amniocentesis or chorionic villus sampling. If you were to know beforehand that you had a baby with Down syndrome, Spina Bifida or an abnormal heart, it may impact on our recommendations for how and where you deliver so that the baby can get the best care possible after delivery.
If your NT ultrasound and blood tests indicate a potential problem, you can undergo Chorionic Villus Sampling (CVS). This is the earliest diagnostic test that can be done; it is performed between 11 and 13 weeks and is highly accurate in ruling out genetic disorders and chromosomal abnormalities, it can also tell you the sex of the baby. A small sample of cells (chorionic villi) are taken from the placenta, either with a needle inserted through the abdomen, or with an instrument inserted through the vagina and cervix, results take between two to three weeks. There is a small increase in risk of miscarriage with the CVS test.
What is NIPT?
Non-invasive prenatal testing (NIPT) is a new way to screen for specific chromosomes changes (mainly Down syndrome, trisomy 13, trisomy 18, and sex chromosomes X and Y) in a developing baby by looking at the baby’s DNA (cell free fetal DNA) that is found in the mother’s blood during pregnancy. The purpose of NIPT is to identify babies that have a high chance of having specific chromosome changes (mainly Down syndrome) without risk to the baby.
What information can NIPT provide?
NIPT can find >99% of developing babies with Down syndrome. It can also be used to tell if a baby has trisomy 13, trisomy 18, or sex chromosome changes; however, NIPT is not as good at finding these chromosome changes compared to looking for Down syndrome. NIPT is not perfect. There is a small chance (<1%) that NIPT will say that a baby does have Down syndrome when, in fact, it does not (i.e. false positive). Similarly, there is a small chance that NIPT will say that a baby does not have Down syndrome when, in fact, it does (i.e. false negative). Increasingly, NIPT is being used to detect chromosomes changes other than those explained above; however, it is important to discuss the reliability of NIPT for other chromosome changes with your healthcare provider.
Who is eligible for NIPT?
In Ontario, OHIP-funded NIPT is offered to women who meet specific eligibility criteria. These criteria include, but are not limited to: advanced maternal age (≥40 years old at delivery), positive maternal multiple marker screening test for Down syndrome or trisomy 18, nuchal translucency ≥3.5mm, previous child with Down syndrome, trisomy 13, or trisomy 18, or an ultrasound soft marker or abnormality suggestive of a chromosome change. Women who do not meet the eligibility criteria can pay for the screen themselves, prices may vary but costs are generally between $800 - $1000.
Is NIPT appropriate for all pregnancies?
NIPT is available for singleton pregnancies. While some companies do offer NIPT for twin gestations and pregnancies achieved using an egg donor, most companies do not. Additional restrictions do exist; it is important to review each company’s eligibility criteria. NIPT can be used if you’ve had a previous pregnancy because the baby’s DNA (cell free fetal DNA) is gone from the mother’s blood just hours after the baby is born.
How and when is NIPT done?
Currently, NIPT is offered in Canada through the following labs:
NIPT can be ordered by your primary care provider or a genetics clinic. NIPT is done by taking a blood sample from the mother as early as 9 or 10 weeks of pregnancy. An ultrasound is needed before having NIPT to date the pregnancy accurately and to determine if there is one or multiple babies. An ultrasound is not needed at the time the blood test is taken.
Are there any risks of NIPT to the baby?
NIPT is a blood test done on the mother. It does not hurt the developing baby and does not increase the chance of a miscarriage. This is different from other types of testing such as CVS (chorionic villus sampling) and amniocentesis.
What type of result could I receive?
NIPT provides a “high risk” or “positive” or “low risk” or “negative” result for each of the conditions screened. If the NIPT result is high risk/positive, more testing is offered to see if the baby really has the chromosome change. This is done by diagnostic tests called chorionic villus sampling (CVS) or amniocentesis. CVS and amniocentesis tell for sure if the baby has Down syndrome, trisomy 13, trisomy 18, or sex chromosome changes. Both amniocentesis and CVS have a small chance of miscarriage. No irrevocable obstetrical decision should be made in pregnancies with a high risk/positive NIPT result without confirmatory invasive diagnostic testing.