Blood tests before pregnancy: folate, iron, thyroid, vitamin D and blood sugar

Some of the most important weeks of a baby's development happen before many women know they are pregnant. That is why doctors and midwives encourage a health check before trying to conceive. A blood test is one part of it. It can pick up low iron, thyroid problems or raised blood sugar while there is still time to act.

This article is general health information. If you are planning a pregnancy, see a doctor or midwife for pre-pregnancy advice, especially if you have a medical condition or take regular medication.

Folate

Folate is a B vitamin needed for cell division and for the healthy development of the baby's brain and spinal cord in the first weeks of pregnancy. LifePrint uses the World Health Organization's 2015 threshold, where a serum folate below 10 nmol/L is deficiency.

A normal folate result is reassuring, but it does not replace folic acid. Taking folic acid from before conception into early pregnancy lowers the risk of neural tube defects such as spina bifida, and this advice applies whatever your blood level. Some women need a higher amount than usual, for example those with diabetes, a previous affected pregnancy or certain medicines. Ask a doctor, midwife or pharmacist which is right for you.

Iron and haemoglobin

Pregnancy greatly increases the body's need for iron, to build extra blood and to supply the baby. Women who start pregnancy with low stores are more likely to become anaemic, which is linked to tiredness and to poorer outcomes for mother and baby. Building up iron before conception is easier than catching up during pregnancy.

Under the WHO 2020 ferritin guideline, a ferritin below 15 ug/L in an adult means iron deficiency. LifePrint shows 15 to 30 ug/L as a grey zone of low stores, which is worth raising with your doctor if you are planning a pregnancy. For haemoglobin, the WHO 2024 cut-off for anaemia in non-pregnant women is 12.0 g/dL. Pregnancy has its own cut-offs, which your doctor or midwife will use once you are pregnant.

Thyroid

Thyroid hormone is essential for the baby's early brain development, and in the first months the baby depends on the mother's supply. An underactive thyroid that is not treated is linked to miscarriage and other complications. The Well Woman panel includes TSH and TPO antibodies.

• A raised TSH should be discussed with a doctor before you try to conceive. Targets before and during pregnancy are stricter than for other adults.
• Positive TPO antibodies with a normal TSH do not mean thyroid disease now, but they raise the chance of an underactive thyroid developing during pregnancy. Your doctor may want to check your thyroid again early in pregnancy.
• If you already take thyroid medication, tell your doctor as soon as you find out you are pregnant, because the dose often needs adjusting early.

Vitamin D

Vitamin D supports calcium absorption and bone health for you and the baby. LifePrint uses the Institute of Medicine thresholds: below 30 nmol/L is deficient, 30 to 50 nmol/L is insufficient and shown in the grey zone, and 50 nmol/L or above is sufficient. Very high levels, above 125 nmol/L, can cause harm, so supplements should be guided by your result and your doctor.

Blood sugar

High blood sugar in the early weeks of pregnancy raises the risk of miscarriage and of problems with the baby's development. Type 2 diabetes often has no symptoms, so a blood test is the only way to know. LifePrint follows the SEMDSA 2017 guideline: an HbA1c of 6.5% or above, or a fasting glucose of 7.0 mmol/L or above, is in the diabetes range and needs confirming. An HbA1c from 6.0 to 6.4% or a fasting glucose from 6.1 to 6.9 mmol/L sits in the grey zone.

Tests that are not in this panel

Your doctor or midwife may also suggest checking immunity to rubella, your blood group, and screening for HIV, syphilis and hepatitis B. An STI screen covering HIV, syphilis and hepatitis B is available as a LifePrint add-on. A review of your medicines is also important, because some are not safe in pregnancy. Do not stop a prescribed medicine without advice.

Once you are pregnant, antenatal care includes its own set of blood tests, and your doctor or midwife will guide those. If anything in your LifePrint report is flagged, take it to a registered healthcare practitioner before you start trying.