Common Clinical Words Related to Pregnancy

COMMON CLINICAL WORDS

Certain words are used repeatedly while discussing issues related to pregnancy. A brief description of the meaning of each word is given on this page.

Zygote – The single cell that results from the fertilization of the ovum by the sperm.

Embryo – When the single celled zygote starts to divide, it is called an embryo. The term embryo is used until the end of the eighth week of pregnancy. At this stage, it is 3.5 cm in length and about 2gms in weight.

Fetus – The word fetus is used to describe the developing baby from the end of the eighth week till the last week of pregnancy. From the eighth week onwards, the foetus floats freely in the liquor amnii connected to the uterus only by the umbilical cord. It is able to move and swim in the liquor and begins to show features of a human being, with development of eyes, ears and limbs.

Last Menstrual Period (LMP) – This is the last menstrual period that a woman has had before she became pregnant.

The Expected Date of Delivery (EDD) - or the Expected Due Date is the date at which the baby is expected to be delivered. This is calculated from the first day of the Last Menstrual Period (LMP). Two methods are usually employed to calculate the EDD:

Nine months are calculated from the first day of the LMP and seven days are added to the answer. For example, if the LMP is 3rd March, the EDD will be 3rd December plus seven days, that is 10th December.

Three months are counted backwards from the first day of the LMP and seven days added to the answer. For example, if the LMP is 3rd March, three months counted backwards will take us to the 3rd of December. Seven days added to it will be 10th December.

But these methods are accurate only if the menstrual cycle is regular and 28 +/- 2 days. If cycle length is longer, say 32 days then the extra days beyond 28 days, i.e 4 days have to be added to the EDD.

So a woman whose LMP was on the 3rd of March, but whose cycle length is 32 days will have her EDD on the 9 months +7days +4 days = 3rd December +7days+4days= 14th December. Similarly if the cycle length is less, the same number of days have to be subtracted from the calculation. Only about 10% of women deliver on the EDD.

Most women deliver within the first week of the EDD. Delivery between three weeks before and two weeks after the EDD is considered normal.

Trimester - The entire duration of pregnancy is divided into three parts for the purposes of management of pregnancy. Each division, called a ‘trimester’ is approximately 13 weeks long :

1st Trimester – from the beginning of pregnancy till the end of the twelfth week.

2nd Trimester – from the beginning of the 13th week to the end of the 28th week.

3rd Trimester – from the end of the 28th week to the end of the 40th week.

Lie – This is the relation of the fetal spine with that of the maternal spine. If the fetal spine is more or less parallel to that of the maternal, the lie is said to be ‘Vertical’. In most babies, the lie is vertical. If the foetal spine is at a right angle to the maternal spine, the lie is ‘Transverse’. If the foetal spine is oblique across the maternal spine, the lie is ‘Oblique’. This is also a common lie. At the time of labour, when the uterus starts to contract, this lie quite often changes to Vertical. If the lie of the foetus is found to change very often, it is called an ‘Unstable lie’.

Presentation - This depends on the part of the foetal body that presents at the cervix at the time of labour.

Abortion – Although the word ‘miscarriage’ is freely used to describe the loss of a foetus in early weeks of pregnancy, the correct medical term is ‘Abortion’. An abortion is said to have occurred when a foetus less than 500 gm in weight or less than 22 weeks of gestational age is expelled from the body.

Ovulation, Fertilization and Implantation - An ovum is released from the ovary approximately 14 days (12 to 16 days) after the last menstrual period. Fertilization occurs when the male sperm meets the female ovum and fuses with it to form the zygote. It usually occurs in the outer part of the fallopian tube. The single celled zygote starts to divides in about 12 hours into 2 cells. It continues to divide into more cells as it is propelled towards the uterus by the ciliary cells lining the inner wall of the tube as well as by the movement of the tube itself. By the time it reaches the uterus it is a cluster of sixteen cells called a 'morula'.

The morula reaches the uterine cavity and becomes attached to the inner lining of the uterus (the endometrium) on the 6th day after ovulation. It begins to burrow into the spongy endometrium and by the 10th day, it is completely embedded in it and begins to develop into a baby. The process of embedding into the endometrium is called ‘Implantation’.

This site is a Question and Answer Site on Obstetrics and Gynecology . Here you can ask any medical health question you like from the privacy of your home. And our online gynecologist Dr.M.D.Mazumdar, MD (O&G), will reply within 24 hours.

The advantage of online consultation is that you can ask your question from the privacy of your home at any time you want - morning, day or midnight. You can plan out what you want to ask or even prepare a questionnaire about your concerns. Our expert would be glad to answer every detail.

We charge a nominal fee of USD 20 ($20) per question (for Indian viewers, the charge is a discounted USD 9, about Rs 400.00 only) to help keep this site up and running. All payments are made through the third-party Paypal credit card processing system to ensure absolute credit card security and reliability.

The procedure of asking a question is quite simple. Clicking on the link below takes you to the Paypal website where the payment is made. After the payment goes through, you will be directed back to this website where you can ask your question.

And rest assured, you will get your answer within 24 hours. And usually, even sooner.

COMMON CLINICAL WORDS

OTHER TOPICS IN NORMAL PREGNANCY: