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Tests and monitoring in pregnancy
Pregnancy tests explained
Most pregnancy tests are not there to create anxiety. They are there to answer a practical question: is the pregnancy progressing as expected, is there something treatable we should pick up early, and does anything about you, the placenta, or the baby mean the plan should change?
This page explains the routine blood tests, urine tests, blood-pressure and urine monitoring, the glucose tolerance test, GBS screening, growth scans, and umbilical artery Doppler in plain language. The NT and detailed anatomy scan already have their own pages, so here they are summarized briefly with links.
Some tests are offered to almost everyone, while others are only added if your history, symptoms, blood pressure, growth pattern, or scan findings give a reason. An abnormal result does not always mean something dramatic, but it usually does tell us what needs to be repeated, treated, or watched more closely.
At a glance
Which tests are routine, and which ones are more targeted?
Pregnancy care is easier to understand when you separate tests into three groups: tests almost everyone has, milestone scans booked at specific windows, and extra tests that are only added when a question appears.
For most pregnancies
Routine bloods, blood pressure, urine checks, glucose testing, and GBS
These tests help pick up issues such as anaemia, blood-group concerns, infection, raised blood pressure, glucose problems, or later-pregnancy colonization that can affect birth planning.
At specific scan windows
The NT scan and the detailed anatomy scan
These are milestone fetal scans answering different questions at different stages. They are not interchangeable, and the timing matters.
Later-pregnancy monitoring
Routine growth scans, plus Dopplers or extra tests when needed
Growth scans form part of routine later-pregnancy follow-up in this practice. Additional tools such as Dopplers, repeat urine cultures, or extra bloods are then added when the pregnancy gives us a more specific question to answer.
Routine does not mean “one size fits all.” It means there is a baseline plan, and then it is individualized if the pregnancy stops behaving like a straightforward low-risk pregnancy.
Early blood tests
What the booking bloods usually test for, and why
Patients are often told they need “routine pregnancy bloods” without anyone unpacking what that actually means. These are the common questions those bloods are trying to answer.
Blood group, Rhesus status, and antibodies
Your blood group means the ABO type of your red blood cells, such as A, B, AB, or O. Your Rhesus status means whether a specific marker called the RhD antigen is present on those red blood cells. If it is present, you are Rh positive. If it is absent, you are Rh negative.
This matters in pregnancy because an Rh-negative patient can sometimes be exposed to Rh-positive fetal blood cells. If that happens, her immune system may form antibodies against those blood cells. In a first pregnancy this may not cause a problem immediately, but in the same pregnancy or in a later pregnancy those antibodies can cross the placenta and affect the baby’s red blood cells.
That is why we check both the blood group and whether antibodies are already present. If you are Rh negative, bleeding episodes, procedures, trauma, and delivery may change the plan because anti-D may be needed to reduce the chance of sensitization. If antibodies are already present, follow-up becomes more specific and may include repeat blood tests and more tailored fetal monitoring.
Full blood count and iron stores
A full blood count checks things such as your haemoglobin level and the size and number of red blood cells. It helps us see whether you are anaemic already, and whether the pattern looks consistent with iron deficiency or another reason for anaemia.
Pregnancy increases iron requirements. Your body needs more iron to support the increase in your own blood volume and the needs of the growing baby and placenta. If you begin pregnancy with low iron stores, you are more likely to drift into symptomatic iron deficiency or anaemia later.
That is why early iron status matters. It helps us decide whether ordinary pregnancy supplements are enough or whether you need more definite iron replacement. These tests may be repeated later in pregnancy, especially if symptoms continue, haemoglobin is not recovering as expected, or we think IV iron may be more useful because oral supplementation is not enough or is not being absorbed or tolerated well.
Infection screening
Routine pregnancy bloods commonly screen for infections such as HIV, syphilis, and hepatitis B. These are not included because we assume someone is unwell. They are included because these infections can sometimes be present quietly, remain unnoticed for a long time, or be dormant or latent, while still having a major effect on pregnancy and on the baby if they are not recognized.
Each of these infections matters for a slightly different reason. Some can cross to the baby during pregnancy, some can affect birth management, and some can change newborn treatment immediately after delivery. The value of screening is that once we know, we can usually reduce risk substantially with the right treatment and planning.
A positive result does not simply become “one more number on the blood form.” It changes care in practical ways, which is exactly why we screen early rather than waiting until a complication forces the question later on.
Down syndrome screening bloods and NIPT
These screening blood tests also belong in the early pregnancy blood-test conversation. Even though they are optional and patients can choose to opt out, they are still commonly offered as part of routine first-trimester pregnancy care because the timing is important and the decisions need to be made early.
There are two broad pathways patients usually hear about. One is the combined first-trimester screening pathway, where the lab measures pregnancy-related markers such as PAPP-A and beta-hCG and interprets them together with the NT scan, your dates, and your age to estimate chance. The other is NIPT, which is a blood test from your arm that looks at placental DNA in your bloodstream to estimate the chance of common chromosomal conditions such as Down syndrome, trisomy 18, and trisomy 13.
These are screening tests, not diagnostic tests. Their role is to estimate chance and help decide whether no further testing is needed, whether a scan-based conversation needs to be clearer, or whether diagnostic testing should be discussed. The fuller explanation of these choices, including timing and how they fit with the NT scan, is on the first-trimester screening page.
Rubella immunity
Rubella immunity is usually checked to see whether you are already protected from German measles. The live rubella vaccine is not given during pregnancy, so this result is mainly about knowing how carefully we need to think about exposures and what should be offered after birth if you are not immune.
If you are not immune, that information helps guide counselling if there is contact with someone who has an active rash illness or a suspected rubella exposure during pregnancy. It also matters for future protection, which is why postpartum vaccination is often part of the plan.
Not routine for everyone
Sometimes other targeted blood tests are added early
Depending on your history, extra blood tests may be useful even though they are not routine for every pregnancy. Examples include thyroid testing, clotting-related tests, follow-up after a previous pregnancy complication, medication-related monitoring, or another medical reason to ask a more specific question early rather than late.
If one of these blood tests is abnormal, the result usually does not stand alone. It changes what we repeat, treat, or monitor next. That may mean iron treatment, anti-D planning, repeat antibody testing, infection treatment, or referral when a more specialist pathway is needed.
Urine tests
Urine dipsticks, urine MCS, and why urine keeps being checked
Urine testing in pregnancy is not all the same thing. A dipstick in the rooms answers different questions from a urine MCS sent to the lab.
Urine dipsticks at routine visits
A urine dipstick is the quick test often done in the rooms. It can show clues such as protein, blood, glucose, white cells, or nitrites. It is useful because it is immediate and can help us decide whether there is a reason to look further.
It is important to understand that a dipstick is a screening test, not a full diagnosis. A small abnormality on a dipstick may mean we repeat the sample, correlate it with symptoms and blood pressure, or send a proper urine culture if infection is part of the question.
Urine MCS: what it means and when we send it
Urine MCS stands for microscopy, culture, and sensitivity. This is the laboratory urine test used when we want to know whether bacteria are really present, what organism is growing, and which antibiotics are most likely to work.
We use it when symptoms suggest a urine infection, when the dipstick is suspicious, when there is recurrent infection, or when we want to make sure treatment has genuinely cleared the bacteria rather than just improved symptoms temporarily.
Why urine infection matters more in pregnancy
Urine infection in pregnancy matters because even an infection that seems mild can lead to bigger problems than it might outside pregnancy. It can make you feel unwell, progress to a kidney infection, trigger contractions, and complicate the pregnancy if it is missed.
That is why pregnancy has a lower threshold for testing and treating suspected urine infection. The aim is not to overmedicalize minor symptoms. It is to avoid allowing a preventable infection to sit quietly in the background.
Protein in the urine and why we check it with blood pressure
Protein in the urine matters most when blood pressure is also part of the picture. On its own, it does not automatically diagnose pre-eclampsia, but it becomes much more significant if a patient has raised blood pressure, headache, visual symptoms, upper abdominal pain, or is suddenly unwell.
That is why urine and blood pressure are often checked together. They help us decide whether this is just a single borderline reading, a temporary blip, or part of a pregnancy that needs a more urgent pre-eclampsia work-up.
If you have burning urine, frequency, fever, back pain, or a positive urine culture, the next step is usually pregnancy-safe antibiotics and sometimes a repeat urine culture to make sure the infection has actually cleared.
Scans with their own pages
Short summaries of the milestone scans
These scans deserve their own fuller explanations, so here the aim is only to place them in context and link you to the detailed pages.
11 to 14 weeks
NT scan and first-trimester screening
This is the early screening stage. Depending on what you choose, it may involve the NT scan, combined screening bloods, or NIPT. The timing matters because this window closes.
20 to 22 weeks
Detailed anatomy scan
This is the main structural scan of pregnancy. It looks carefully at anatomy, placenta, fluid, and the broad way the pregnancy is developing. It is not the same as a quick routine follow-up scan.
Later in pregnancy
Growth scans are different again
Growth scans are not the same as the NT scan or the anatomy scan. They are the later-pregnancy scans used to review growth, fluid, position, and the broader picture of how the pregnancy is progressing.
Growth scans and Dopplers
What growth scans look at, and what an umbilical artery Doppler means
In this practice, growth scans are part of routine later-pregnancy care. They help keep track of how the baby is growing, how the fluid looks, how the baby is lying, and whether the overall pregnancy picture remains reassuring.
What a growth scan checks
Growth, fluid, position, and the general late-pregnancy picture
A growth scan usually estimates the baby’s size, looks at interval growth over time, checks the fluid around the baby, reviews presentation, and gives a broader sense of whether the pregnancy is tracking as expected.
Why they matter
Routine growth review helps us see the pattern, not just one moment
Regular growth review is useful because it lets us see whether growth is staying on track over time rather than making assumptions from one single late-pregnancy impression. It also helps bring size, fluid, and the rest of the pregnancy picture into one conversation.
Umbilical artery Doppler
This is a blood-flow check, not a different baby scan
A basic umbilical artery Doppler measures how blood is flowing through the cord artery and gives clues about the resistance the placenta is creating. It is one of the extra tools used when we want a closer look at placental function, especially if growth or the broader clinical picture raises concern.
What if the scan is abnormal?
The next step is usually closer follow-up, not immediate panic
An abnormal growth scan or Doppler may lead to repeat scans, fetal monitoring such as CTG or NST, blood-pressure review, specialist scanning, or a conversation about whether the safest timing of birth is shifting.
Growth scans are estimates, not exact birth-weight predictions. The value is usually in the pattern over time and in whether the scan fits with the rest of the clinical picture.
Glucose tolerance testing
How the 2-hour OGTT works, what to expect, and what happens if it is abnormal
The glucose tolerance test is used because pregnancy can unmask a problem with how your body handles sugar. In this practice, the test is a 2-hour OGTT. Gestational diabetes matters because it can affect the baby’s growth, birth planning, and the mother’s longer-term health, but it is very manageable when picked up properly.
A positive result is not mainly about blame or diet guilt. It is about recognising a pregnancy that needs a more structured glucose plan.
Practical guide
What to expect with the 2-hour OGTT
- Who often has it: most patients are screened around 24 to 28 weeks, while some higher-risk patients may be tested earlier or more than once.
- How to prepare: this is a fasting test, so you arrive without eating. The lab will usually guide the exact fasting window, but the practical point is that it is not a casual drop-in blood test after breakfast.
- What happens on the day: a fasting blood sample is taken first, then you drink the glucose load, and further blood samples are taken at timed points over the next two hours.
- What the drink is like: the glucose drink is very sweet, and some patients feel nauseous or lightheaded while waiting. It is not dangerous, but it is not everyone’s favourite test.
- If it is abnormal: the next step may include glucose monitoring, nutrition support, exercise advice, and medication or insulin if needed.
- What changes later: growth follow-up, delivery planning, and postpartum diabetes follow-up may all be adjusted.
- What it does not mean: an abnormal test does not automatically mean you were diabetic before pregnancy or that something has already gone badly wrong.
If the drink makes you feel very nauseous, tell the lab staff rather than just struggling through it silently. Some patients tolerate the test perfectly well, while others find the glucose load unpleasant.
The 2-hour OGTT is still a blood test pathway, but it is more structured than the routine booking bloods because timing matters. The result helps distinguish a pregnancy with normal glucose handling from one that needs a gestational diabetes plan.
GBS screening
When the GBS screen is done, why we do it, and what a positive result means
The GBS swab is not checking for a sexually transmitted infection. It is checking for Group B streptococcus, a bacteria that can live quietly in the vagina or bowel and matter mainly at the time of labour and birth.
When
The swab is usually done in late pregnancy
The timing is usually chosen close enough to birth to make the result useful for labour planning. In practical terms, this is a later-third-trimester test rather than an early pregnancy screen.
Why
The aim is newborn protection, not to prove you are ill
A positive GBS result usually means colonization rather than infection. The concern is that the bacteria can be passed to the baby during labour or after the waters break.
If positive
The labour plan usually changes more than the pregnancy itself
If the swab is positive, the usual conversation is about antibiotics in labour and how birth is managed, not about doing repeated treatment throughout the rest of pregnancy when you feel well.
A positive GBS swab does not mean the baby is infected and it does not mean you have done anything wrong. It means the birth plan often includes antibiotic cover in labour to reduce early newborn infection risk.
CTG and NST monitoring
What a CTG or NST is, and why it sometimes becomes part of pregnancy care
A CTG or NST is not part of every routine visit, but it is a common pregnancy assessment. It is used when we want to know how the baby’s heartbeat is behaving over time and whether the pattern looks reassuring in that moment.
What it is
A heart-rate tracing over time
You may hear this called a CTG or an NST. It usually involves monitors on the abdomen that record the baby’s heartbeat and often uterine activity over a period of time, rather than just listening briefly and moving on.
Why we use it
It helps answer a specific reassurance question
This test may be used if movements feel reduced, if blood pressure is part of the picture, if a growth or Doppler scan raises concern, if the pregnancy has become higher risk, or if we simply need a clearer same-day sense of fetal wellbeing.
What it does and does not do
It is useful, but it is still one moment in time
A reassuring CTG or NST is valuable, but it does not replace the rest of the pregnancy assessment. Depending on the situation, it may sit alongside ultrasound, growth review, Dopplers, blood pressure review, and the wider clinical picture.
The practical message is that CTG or NST monitoring is common in pregnancy care even though it is not a routine screening test for everyone. It is usually done because there is a reason to ask a more immediate question about the baby’s current wellbeing.
Blood pressure and urine monitoring
How blood pressure is taken in pregnancy, why urine is checked with it, and how we interpret the result
Blood pressure is one of the simplest routine checks in pregnancy, but it matters because it is one of the main ways we screen for gestational hypertension and pre-eclampsia. The number itself matters, but so does the context, the symptoms, and the urine result that sits next to it.
One rushed reading is not the whole diagnosis, but a genuinely raised reading should not be brushed aside because you feel otherwise well.
What we are looking for
Blood pressure makes more sense when you see the whole check together
- How it should be taken: you should be seated, reasonably settled, with the arm supported and a cuff size that actually fits. If the reading is high, it is usually repeated rather than accepted blindly.
- What counts as raised: repeated readings at or above 140/90 usually need medical review, and a severe reading such as 160/110 or higher is more urgent.
- Why urine is checked as well: protein in the urine can be one of the clues that raised blood pressure is part of pre-eclampsia rather than only a blood-pressure number in isolation.
- What happens if there is concern: the next step may include repeat blood pressure, urine protein review, blood tests, fetal assessment, and a clearer same-day plan.
- Why symptoms still matter: headache, visual change, upper abdominal pain, breathlessness, or sudden swelling can matter even before a diagnosis is fully established.
Frequently asked questions
Common questions about pregnancy tests and monitoring
What do the routine booking bloods usually include?
They commonly include your blood group and Rhesus type, an antibody screen, a full blood count, and screening for important infections and immunity questions in pregnancy. Depending on your history, iron stores or other targeted blood tests may be added as well.
What if I am Rh negative?
Being Rh negative does not automatically mean something is wrong, but it can change how bleeding episodes, anti-D treatment, and antibody follow-up are handled later in pregnancy. That is why it is worth knowing early.
What is a urine MCS?
Urine MCS stands for microscopy, culture, and sensitivity. It is a lab test used to confirm whether bacteria are really present in the urine and which antibiotics are likely to work, rather than just guessing from symptoms or a dipstick.
What do routine growth scans actually look at?
Routine growth scans usually look at estimated fetal size, interval growth over time, the fluid around the baby, presentation, and the broader late-pregnancy picture. If something needs a closer look, extra tools such as Dopplers or additional monitoring may then be added.
What is an umbilical artery Doppler?
It is a blood-flow measurement in the cord artery used mainly when placental function is part of the question. It helps show whether the placenta may be offering more resistance than expected, especially in a baby who may be smaller than expected.
What is a CTG or NST in pregnancy?
A CTG or NST is a period of fetal heart-rate monitoring used when we want to know whether the baby’s heartbeat pattern looks reassuring at that moment. It is not part of every routine visit, but it is a common assessment when reduced movements, blood pressure concerns, growth questions, or another higher-risk feature means we need a clearer same-day picture.
How should I prepare for the 2-hour OGTT, and what should I expect?
This is a fasting test, so it is not the sort of blood test you do casually after breakfast. A fasting sample is taken first, then you drink the glucose load, and more blood samples are taken over the next two hours. The drink is very sweet and some patients feel nauseous, but the test is generally safe and gives useful information about how your body is handling glucose in pregnancy.
What happens if the glucose tolerance test is abnormal?
An abnormal result usually leads to a gestational diabetes plan rather than immediate panic. That may include glucose monitoring, nutrition and exercise advice, medication if needed, and follow-up that pays closer attention to growth and birth planning.
What does a positive GBS swab mean?
It usually means you are colonized with Group B streptococcus, not that you have an active infection making you ill. The main consequence is that labour care often includes antibiotics to reduce newborn infection risk.
What blood pressure is considered high in pregnancy?
Repeated readings at or above 140/90 usually need review. A severe reading such as 160/110 or higher is more urgent. The symptoms, the urine result, and the rest of the pregnancy picture still matter as well.
Next steps
Use the tests as information, not as background noise
The point of pregnancy testing is not to create a long checklist for its own sake. It is to answer useful questions at the right stage, pick up problems early when they are treatable, and know when the pregnancy needs more than routine follow-up.