What happens when your baby is overdue?

Going overdue and having a post-term or prolonged pregnancy can be very frustrating, because it is only natural that you are eager to meet your new baby. Feeling heavy, uncomfortable and coping with backache and sleepless nights can easily take their toll on the most patient of expectant mums and dads! Going overdue can also be emotionally unsettling, as women, their partners and families use the EDD (estimated date of delivery) to make preparations for the arrival of their new baby, including planning maternity/paternity leave, preparing the baby’s nursery and arranging for friends and family to help out in the early days after the birth.

We have written this article to help explain the options available to you, should your pregnancy go overdue. We recommend that you also discuss these options with your midwife and doctor, so that you are able to make a fully informed decision that feels right for you and your baby.

The normal length of pregnancy

The normal length of a human pregnancy is calculated by taking the first day of the last menstrual period (LMP) and adding on nine months and seven days – this works out to being around 280 days or 40 weeks. A ‘term’ pregnancy is defined as being between 37 – 42 completed weeks of pregnancy. Where a baby is born before 37 weeks of pregnancy this is described as being a preterm birth. Where labour begins after 42 weeks this is called a post-term birth.

Dating scans

All pregnant women are offered a ‘dating scan’ in early pregnancy which is usually performed at between 10 -13 weeks. However, it’s your choice whether you have a dating scan and some women will choose not to. The dating scan calculates when your baby is due to be born and women are given an EDD. The EDD helps the midwives and doctors to monitor the key stages of the baby’s development and to assess their health and wellbeing as the pregnancy advances. It is important to remember that this date is an estimated guide only, as scientists have never been able to predict the exact date a woman will go into labour.  In fact, only four out of every 100 babies born, arrive on their EDD.

Why do some pregnancies go overdue?

While every pregnant woman is given an EDD for her baby’s birth, some will end up going into labour earlier than expected, while others will find their pregnancies go beyond their due date. It isn’t clear why some pregnancies go overdue; however, there is some research evidence that suggests post-term pregnancy may be linked to racial and genetic (hereditary) factors. Similarly, some evidence suggests that seasonal variations and working shifts patterns may also play a role in prolonged pregnancies. There is also some evidence which indicates going overdue is more common if you are expecting a baby boy; similarly, that some rare congenital (birth) abnormalities are associated with post-term pregnancies because they interfere with the body’s natural mechanisms that encourage labour to begin.

What are the risks of going overdue?

Most babies are born healthy regardless of whether they arrive around their due date or end up staying in utero (inside the womb) for a little longer. The midwives and doctors will monitor your baby’s health and wellbeing throughout pregnancy to ensure your baby is growing as they should be, are healthy, and in a good position for labour and birth.  Research shows us that where pregnancies continue beyond the EDD there is an increased likelihood of problems during labour which mean the baby might need to be delivered by caesarean section. There is also an increased risk of having a difficult birth and the baby being born with a low Apgar score (ie being born in a poor condition). See also our article, ‘What is the Apgar score?’ The risk of having more severe complications is also marginally increased however, this risk still remains low. Because these risks can be avoided, the midwives and doctors looking after you will discuss the various benefits and disadvantages associated with (a) allowing pregnancy to continue beyond the EDD so that labour begins naturally, or (b) using medical interventions to encourage labour to start and speed up uterine contractions.

Meconium-stained liquor

Meconium-stained liquor is where the baby has its bowels open (does a poo) while they’re still inside the uterus (womb). Meconium is a thick, sticky dark green/black stool (poo) that can pass into the amniotic fluid (the waters) surrounding the baby, or is passed at the time of the birth. In the vast majority of cases, passing meconium does not cause any problems; particularly where there is a lot of amniotic fluid still around the baby and the meconium is thin. However, occasionally babies will breathe meconium into their lungs which can cause serious breathing difficulties as it is thick and sticky and clogs up some of the small air passages inside the lungs – this condition is called meconium aspiration and babies affected in this way will need to be cared for in a neonatal intensive care unit (NICU). Babies who are born after 42 weeks are more likely to have meconium-stained liquor; however, research has shown that the risk of meconium aspiration can be significantly reduced where labour is induced before 41 completed weeks of pregnancy.

Where babies are born after 42 weeks, they are more likely to need assistance at birth and to be admitted to NICU. This has been found to be the case even where labour has been induced. Pregnancies that continue beyond 42 weeks are also associated with an increased risk of intrauterine death (where the baby dies before labour starts) and stillbirth (where the baby dies during labour). The risk of this happening is increased further where the baby is smaller than average and is underweight – this is called ‘small for gestational age’.

Baby’s size

It is widely recognised that babies put on more weight during the last two weeks of pregnancy. Therefore, where a pregnancy continues beyond the EDD, it is more likely to result in the birth of a larger baby. Bigger babies tend to have more difficult births and are more likely to be born with a low Apgar score.

Monitoring health and wellbeing

Towards the end of your pregnancy, your midwife and doctor will normally see you a lot more often to ensure that you and your baby are healthy. Currently, women with straightforward, uncomplicated pregnancies will be offered induction of labour between 41 – 42 weeks of pregnancy. However, it is your choice as to whether you want to take up this option or not. Some women prefer not to and would rather wait for labour to start naturally, without any interventions. Where this is the case, you and your baby’s health and wellbeing will be monitored regularly to check that all is as it should be. This approach is referred to as ‘expectant management’ or ‘watchful waiting’. Research suggests that women who decide to opt for watchful waiting are very likely to go into spontaneous labour before 42 completed weeks of pregnancy without serious complications/risks to their baby. The evidence also shows however, that most women will make an informed decision to be induced after 41 weeks’ of pregnancy in preference to watchful waiting.

How will my baby’s health be monitored?

There are a range of tests that are used to help the midwives and doctors assess your baby’s health and wellbeing. These tests are normally undertaken in your local maternity unit/hospital, so you will have to go there regularly, sometimes even daily, and are likely to need to remain in for a number of hours while all the tests are done. They include the following:

Monitoring your baby’s heartbeat – this is done using an electronic fetal heart rate monitor (cardiotocograph – CTG). Your baby’s heart rate and pattern gives an indication of how happy they are inside the womb. However, the CTG can not predict how they will cope with uterine contractions once labour has begun. See also our article, ‘Monitoring your baby’s heart rate in labour’

Measuring the volume amniotic fluid (liquor) surrounding the baby – this is done using an ultrasound scan. The volume of fluid normally diminishes as the pregnancy continues beyond the EDD. The amount of amniotic fluid present gives the doctors an indication as to whether it is in the best interest of the baby’s health to allow the pregnancy to continue until labour begins naturally

Measuring the baby’s overall growth – The doctors and midwives use an ultrasound scan to measure the baby’s size to ensure there are no concerns with their growth. The ultrasound scan can also check the blood flow through the baby’s umbilical cord – this is referred to as ‘end diastolic flow’. Where the baby is not growing as it should be, this is referred to as ‘growth restriction’. This can indicate that the placenta is not working as well as it should be and your baby may not be receiving the nourishment they need to grow.

The results of all the above tests are looked at collectively and they enable the doctors to assess your baby’s health and wellbeing, and to determine whether it is safe for the pregnancy to continue with watchful waiting, or recommend that your labour is induced. Where the doctors and midwives have concerns that your baby is safer being born than remaining in utero, they will always explain the reasons why they are recommending induction of labour. However, your labour will not be induced without you understanding what is involved and your informed consent.

What are the disadvantages of being induced?

There are a number of disadvantages associated with induction of labour:

• Research has shown that induction of labour is associated with labours being more painful; this is because the contractions are stimulated by the manmade hormone, oxytocin which has a much more vigorous action
• It can take longer for established labour to begin. See our article ‘The ‘Latent phase’ of labour’
• Babies need to be monitored more closely when labours are induced and the doctors and midwives, in some cases, may recommend that your baby’s heart beat is monitored continuously
• You are more likely to need assistance to deliver your baby using forceps, the ventouse, or by caesarean section.

How will my labour be induced?

Labour can be induced in a number of ways:

• Stimulating labour to start naturally
• Amniotomy also called ‘rupturing the membranes’ (ie breaking the waters surrounding the baby)
• Using drugs eg Prostaglandins and Oxytocin

Natural approaches to stimulating labour

There are a number of traditional remedies and complementary therapies that are often used to encourage labour to begin. These include the following:

Having sex – research has found that having sex (intercourse) encourages the release of hormones – called prostaglandins, which can help to stimulate and prepare the neck of the womb (cervix) for labour. Prostaglandin is also present in semen. However, if you have a low-lying placenta (placenta praevia) you will be advised against having penetrative sex as this can cause severe bleeding (haemorrhage)

Stimulating your nipples and breasts – research has found that women with uncomplicated straightforward pregnancies who stimulate their nipples and breasts every day from 39 weeks’ of pregnancy onwards are less likely to go overdue. There is evidence to also suggest that daily nipple and breast stimulation can reduce the risk of bleeding after the birth – this bleeding is called postpartum haemorrhage. See also our article, ‘Blood loss after your baby’s birth’

Castor oil – this tastes horrid and contrary to the ‘old wives’ tale is not recommended as a method of stimulating labour. Much more research is needed to look at its use as a method of inducing labour

Raspberry leaf tea – this herbal remedy can be bought as either tablets or a drink. It should not however, be used before 36 completed weeks of pregnancy and should be taken daily, starting off with a small amount and gradually increasing this to get to the recommended dose. Raspberry leaf tea has been used historically for a great many years and is believed to tone the uterine muscles so that labour contractions are more effective. Raspberry leaf tea is also thought to help prepare the cervix for labour.  Its use is contraindicated in women who have had surgery to their uterus eg a previous caesarean section or the removal of fibroids. Its use is also contraindicated in women who have had a previous preterm (premature) birth or where the pregnancy is the result of IVF (in vitro fertilisation).

NB. We recommend that you always talk to your midwife, GP or a complementary therapist before taking raspberry leaf tea to ensure that it will be safe for you to take.

Acupuncture – there is some research evidence that suggests acupuncture is safe and effective in reducing the risk of having a post term pregnancy. Women who received acupuncture during pregnancy were found to give birth closer to their baby’s EDD. However, acupuncture should always be undertaken by a qualified acupuncturist and because it is quite invasive, may not be to every woman’s liking. For more detailed information on acupuncture see our article ‘Pain relief options for labour and birth’

‘Stretch and sweep’ – this is performed during a vaginal (internal) examination. Your midwife will run their fingers around and if possible inside the opening of the cervix and will separate the membranes that form the sac (bag) of amniotic fluid from the inside of the cervix. This action helps to stimulate the release of the body’s own naturally occurring prostaglandins and helps to prepare the cervix for labour. Having a ‘stretch and sweep’ can feel quite uncomfortable and may be painful for some women. Your midwife will explain the procedure to you and what is involved, and will gain your informed consent before doing the ‘stretch and sweep’.  Afterwards, it is common to have a pink, red or brown mucousy ‘show’ and you may also notice stronger, niggling Braxton Hicks contractions. However, if you have bleeding or are in anyway concerned, you should always contact your midwife or doctor for their advice.

Medical induction of labour

This is undertaken using a drug called ‘prostaglandin’ which can be given as a vaginal Prostin pessary (tablet) or gel. The pessary/gel is inserted close to the cervix during a vaginal examination and acts directly on the cervix so that it softens and dilates more easily; it also encourages the uterus to start contracting. Prostin tends to be absorbed quickly and a pessary cannot be removed once it has been inserted. They are prescribed by a doctor and inserted in low doses at regular intervals – usually every six hours unless labour begins.

Prostaglandin can also be given in the form of a Propess pessary – this is a pessary that is encased within a fabric pouch which has a long string attached; rather like a tampon! The Propess is inserted so that it lies against the cervix and is left in place for 24 hours. During this time, the prostin releases prostaglandin in controlled doses and acts in the same way to soften the cervix and encourage uterine contractions. Both you and your baby will be monitored closely throughout prostin induction of labour.

In some maternity units women are now being offered ‘outpatient’ induction of labour – they have a Propess inserted and once they’ve had a satisfactory CTG recording of their baby’s heart rate and there are no concerns, return home to await events. The hospital midwives will however, contact them after a few hours to make sure that all is well. If there are any concerns, the woman is advised to come back to the unit/hospital without delay.

Women will often go into established labour after having prostins. However, where this isn’t the case, the prostin usually stimulates the cervix to dilate sufficiently, so that the midwife or doctor can perform an amniotomy (break the waters). Having artificial rupture of the membranes (ARM) will often stimulate the uterus to start contracting – where the uterus does not start contracting or the contractions are irregular or of variable strength and duration, the doctor will advise having an oxytocin infusion (drip) to strengthen and speed up the contractions.

Embarking on induction of labour means that once an informed decision has been made to induce labour, the process needs to continue until the baby is born. This can often mean that there is more clinical intervention eg forceps, ventouse and caesarean sections, but the midwives and doctors will explain the various options available to you, including the benefits and disadvantages associated with each.

And finally …

It is your body, your baby and your birth, so it is important that where you have any questions or concerns, you discuss these with your midwife and doctor as soon as possible. It is important that you understand what is involved and the potential outcomes. Labour and birth can be something of an unknown journey and there are occasions where a baby can begin to struggle with labour induction and becomes distressed (‘fetal distress’). Where this is the case, the midwives and doctors will need to act swiftly to ensure mother and baby’s health and wellbeing are safeguarded.