What is pregnancy?

Reading time: 3 min

Pregnancy is the period running from the moment of fertilisation until the delivery. During this time, which tends to last 40–42 weeks, the expectant mother has to adapt to a series of physical and emotional changes, and also pay special attention to her personal care and diet. Childbirth can occur at any time after week 37 of the pregnancy. It involves three stages; firstly the dilation phase, followed by the baby’s exit from the uterus and it ends with the expulsion of the placenta.

Pregnancy and Childbirth explained in first person

Professionals and patients explain Pregnancy and Childbirth
We recommend going to A&E when you have regular contractions every 5 minutes which do not lessen with rest. Also, this should have been going on for at least 1 hour, for a second birth. In the case of a first birth, we recommend waiting at least 2 hours with contractions. If your waters break, we recommend going to A&E straight away.
I felt very comfortable and I remember it as one of the best times of my life, both physically and emotionally.

It is called pregnancy, gestation or gravida to the period that goes from the implantation of the fertilised egg in the uterus to the time of partum/delivery.

Duration of the Pregnancy

Human pregnancy lasts 40 weeks from the first day of the last menstruation/period, or 38 weeks from fertilisation (approximately 9 months).

Multiple pregnancy

A multiple pregnancy is one in which more than one foetus is developing. This comes about as a result of the fertilisation of two or more ovules, or when the ovule is divided, giving rise, in this case, to genetically identical twins

The double or twin pregnancy is the most common form of multiple pregnancy, although there are certain occasions in which triplet pregnancies occur.

Non-identical twins come from two different ovules, and have two placentas and two sacs. The babies can be of the same or a different gender.


On the other hand, identical twins are produced by the spontaneous division of a single embryo, generated from a single ovule. They are always the same gender and identical. They may share a single placenta, or have two different ones, and can share a single sac, or each one may have their own.

Normal pregnancy and risk pregnancy

normal pregnancy is that which occurs with no unfavourable factors (biological, psychological, socio-demographic, etc.) and/or previous maternal diseases or those acquired during the course of the pregnancy, which may interfere in its normal progression.

Pregnancy is classified into the following levels of risk: low, medium, high, or very high.

The risk assessment is updated in each visit as this can vary. For example, a low risk pregnancy may change to a high risk one if diabetes appears during gestation.

If the pregnancy is considered low or medium risk, a midwife will be your main contact.

high risk pregnancy is one that has more possibilities of developing complications during gestation. In these cases, the woman must be subjected to a more rigorous monitoring, in order to avoid possible risks.

It is estimated that 10% of pregnancies are high risk, and the causes can be very variable and may occur before, during, or after gestation.

If your pregnancy has a high or very high risk, your main contact will be a doctor (obstetric-gynaecologist) and all the specialists that are considered necessary.

Substantiated information by:

Anna Sandra Hernández Aguado
Isabel Benito Díaz
Maria Àngels Martínez Verdú

Published: 20 February 2018
Updated: 20 February 2018

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.


Receive the latest updates related to this content.

Thank you for subscribing!

If this is the first time you subscribe you will receive a confirmation email, check your inbox

An error occurred and we were unable to send your data, please try again later.