Virtual Medical Centre

Stages of Pregnancy

• What is gestational age?
• What is my due date?
• Why is it important I see my doctor regularly during my pregnancy?

This series aims to introduce you to the changes taking place inside the pregnant woman's growing uterus, some of the changes that pregnant women may experience during pregnancy and routine doctor appointments.

What is gestational age?

This series is headed by gestational age. Gestational age refers to the number of weeks since the pregnant woman's last menstrual period (LMP). This differs from the developmental age of the foetus, which depending on the exact time of fertilisation is approximately two weeks less than the gestational age. 

What is my due date?

The expected length of pregnancy in humans is 40 weeks +/- 2 weeks. The due date (expected birth date of your baby) is therefore the date 40 weeks following your last menstrual period. Where your last menstrual period is uncertain, an early dating ultrasound (an ultrasound performed early in the pregnancy with the aim of ageing the embryo) is performed to calculate the age of the foetus and from this information, the expected date of delivery. During the early stages of embryo development there are several key external characteristics (features evident on the surface of the embryo, see Gestational Week 6) that can be used to accurately determine the age of the embryo.

Due date calc

Why is it important I see my doctor regularly during my pregnancy?

Antenatal care refers to the series of doctors' appointments and/or interventions that a woman receives from health care services during her pregnancy. While the majority of care takes place during the pregnancy, antenatal care also includes those appointments and/or interventions related to the pregnancy that occur prior to and following the pregnancy i.e. doctors appointments related to pregnancy planning and optimisation of medical conditions/medication prior to falling pregnant (pre-conception counselling) and care early into the postpartum (following delivery of the baby) period.

A definition from the 1930s that still stands today is that antenatal care is "the whole art of preventive obstetrics". Hence antenatal care acts to prevent or identify and treat conditions that may cause harm towards the foetus/newborn or the mother. In doing so it also aims to help women to have positive pregnancy and birth experiences.

It is important to attend regular antenatal care so that the best health outcomes for both you and your baby can be met. Having an understanding of the changes taking place within your body will help you to understand some of the symptoms that you may experience during your pregnancy and when you should seek help from your doctor.

(In-house- image to go with below links)

Gestational Week 1 - The last menstrual period

Reference

1. Moore KL and Persaud TVN. The developing human: clinically oriented embryology, 7^th ed. 2003. Saunders, Philadelphia. 
2. Gibbs RS, Karlan BY, Haney AF, Nygaard IE (eds). Danforths obstetrics and gynecology, 10^th ed, 2008. Lippincott Williams & Wilkins, Baltimore. 
3. Schoenwolf GC, Bleyl SB, Brauer PR, Francis-West PH. Larsen's human embryology, 4^th ed, 2009. Elsevier, Philadelphia, Pennsylvania.
4. World Health Organisation. What is the efficacy / effectiveness of antenatal care and the financial and organizational implications? Available from <http://www.euro.who.int/__data/assets/pdf_file/0007/74662/E82996.pdf> [2^nd August 2010].
5. Devenish C. Standards of antenatal care. O&G Magazine 2009; 11: 22-23. Available from <http://www.ranzcog.edu.au/publications/o-g_pdfs/O&G-Summer-2009/standards_antenatal_care.pdf> [2^nd August 2010].

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Article Dates:

Created: 16/7/2007

Modified: 26/8/2010

Reviewed: 25/10/2007