Routine Antenatal Investigations For Maintaining Health During Pregnancy

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Maintaining adequate health during pregnancy is important to avoid a range of common pregnancy complications. This article explains a number of routine antenatal investigations offered to pregnant women.

The National Institute for Clinical Excellence (2008) recommends that pregnant women undergo a routine full blood count at 12 weeks and again at 28 weeks gestation. A full blood count will indicate a woman’s ABO blood group – a knowledge of which is essential in the effective management of complications requiring rapid blood transfusion; white blood cell count – which may indicate the presence of infections with the potential to cause negative pregnancy outcomes; rubella immune status – which may indicate the necessity of postpartum vaccination to safeguard future pregnancies against rubella-induced fetal malformations; platelet count – which may indicate the development of common pregnancy hypertensive conditions; haemoglobin levels; and Rhesus D status (DynaMed 2010; DynaMed 2011; DynaMed 2011/2).

A woman who is Rhesus negative and Rhesus antibody negative is at risk of developing Anti-D antibodies in response to Rhesus positive fetal blood, and of undergoing a negative autoimmune reaction against a future Rhesus positive fetus (Joanna Briggs Institute, 2011). In Rhesus negative and Rhesus antibody negative women, routine antenatal Anti-D prophylaxis has been shown to considerably reduce the risk of negative outcomes in subsequent Rhesus positive pregnancies (Crowther & Middleton, 2009). It is therefore recommended that such women receive Anti-D prophylaxis at 16, 28 and 32 weeks gestation (National Institute for Clinical Excellence, 2010).

Iron-deficiency anaemia, indicated by a haemoglobin count of under 10.5g/dL, is a common problem in pregnancy and is also indicated in a full blood count (Reveiz, Gyte & Cuervo, 2010). Anaemia increases the risk of negative pregnancy outcomes, including altered fetal development resulting in low birthweight neonates (Haider & Bhutta, 2009). The midwife should recommend that such women commence daily non-teratogenic iron supplementation to promptly increase her haemoglobin levels to within the recommended parameters (Pena-Rosas & Viteri, 2009). Dietary improvements will also assist in allowing anaemic women to maintain healthy levels of iron throughout their pregnancy (Pena-Rosas & Viteri, 2009).

The other routine blood test offered to women screens for gestational diabetes mellitus. The other primary routine investigation offered to pregnant women is ultrasound examination at 6 to 8 weeks gestation – to determine precise gestational age and to detect multiple pregnancies; at a maximum of 20 weeks gestation – to screen for Down’s Syndrome, neural tube defects and fetal growth anomalies; and at a maximum of 32 weeks gestation – to assess fetal position, placental perfusion and amniotic fluid volume (National Institute for Clinical Excellence, 2008). Urinalysis – to screen for proteinuria, haematuria, bacteruria, keytonuria and glycosuria, etc. – is another routine antenatal investigation completed regularly from 12 weeks gestation (Grigg, 2009).

Non-routine antenatal investigations, to be completed only when indicated, include cardiotocograph, chorionic villius sampling and fetal blood sampling (Viccars, 2009). Optional blood tests – for uncommon infections, haemoglobinopathies and abnormal red blood cell alloantibodies, etc. – may be offered to a woman if her health history indicates that she may be at risk of such conditions (National Institute for Clinical Excellence, 2008).

SOURCES

Crowther, C. A. & Middleton, P. (2009). Anti-D administration in pregnancy for preventing rhesus alloimmunisation. Cochrane Database of Systemic Reviews (Online). doi: 10.1002/14651858.CD000020.; DynaMed. (2010). Asymptomatic bacteriuria [DynaMed Summary]. Retrieved March 24, 2011 from http://search.ebscohost.com.ezp01.library.qut.edu.au/login.aspx?direct=true&site=dynamed&id=AN+435309; DynaMed. (2011). Postpartum haemorrhage [DynaMed Summary]. Retrieved March 24, 2011 from http://search.ebscohost.com.ezp01.library.qut.edu.au/login.aspx?direct=true&site=dynamed&id=AN+114247; DynaMed. (2011/2). Screening and monitoring during pregnancy [DynaMed Summary]. Retrieved March 24, 2011 from http://search.ebscohost.com.ezp01.library.qut.edu.au/login.aspx? direct=true&site=dynamed&id=AN+”114252″; Grigg, C. (2009). Working with women in pregnancy. In Pairman, S., Pincombe, J., Thorogood, C. & Tracy, S. (Eds.). Midwifery: preparation for practice. UK: Churchill Livingstone Elsevier; Haider, B.A. & Bhutta, Z.A. (2009). Multiple micronutrient supplementation for women during pregnancy. Cochrane Database of Systemic Reviews (Online). doi: 10.1002/14651858.CD004905.pub2; Joanna Briggs Institute. (2011). Rhesus D negative women [Evidence based recommended practice]. Retrieved from http://www.joannabriggs.edu.au; National Institute for Clinical Excellence. (2008). Routine antenatal care for healthy pregnant women [Evidence based recommended practice]. Retrieved from http://www.nice.org.uk/nicemedia/pdf/CG062PublicInfo.pdf; National Institute for Clinical Excellence. (2010). Pregnancy – routine anti-D prophylaxis for rhesus negative women [Evidence based recommended practice]. Retrieved from http://www.nice.org.uk/guidance/index.jsp?action=byID&o=12047; Pena-Rosas, J.P. & Viteri, F.E. (2009). Effects and safety of preventative oral iron or iron + folic acid supplementation for women during pregnancy. Cochrane Database of Systemic Reviews (Online). doi: 10.1002/14651858.CD004736.pub3; Reveiz, L., Gyte, G.M.L., & Cuervo, L.G. (2010). Treatments for iron-deficiency anaemia in pregnancy. Cochrane Database of Systemic Reviews (Online). doi: 10.1002/14651858.CD003094.pub2; Viccars, A. (2009). Antenatal Care. In Fraser, D.M. & Cooper, M.A. (Eds.). Myles Textbook for Midwives (pp. 263-287). UK: Churchill Livingstone Elsevier.

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