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Does IVF increase the risk of preterm birth? We explain
Victoria 
Table of contents
If you’re considering in vitro fertilisation (IVF) treatment, it’s normal to have questions about its safety. You may have read that some studies suggest IVF is associated with a higher risk of preterm birth compared with a spontaneously conceived pregnancy. Current scientific evidence does not show a direct cause-and-effect relationship between IVF and preterm birth. Rather, the risk of preterm birth following IVF is mainly explained by the patient’s clinical profile, maternal age or certain medical conditions, and not by the assisted reproduction technique itself.
Today, in clinics specialising in in vitro fertilisation, such as Tambre, more precise embryo selection makes it possible to transfer embryos with a higher potential for implantation and a favourable pregnancy outcome, which may help reduce the risk of preterm birth following IVF.
Evidence on the extent of the risk
Current scientific evidence indicates that the risk of preterm birth in IVF pregnancies is only slightly higher than in the general population.
Studies suggest that it is not in vitro fertilisation itself that directly causes preterm birth, but rather pre-existing factors such as maternal age, associated medical conditions or the patient’s obstetric history. In fact, when women with similar clinical characteristics are compared, the differences between spontaneously conceived pregnancies and IVF pregnancies virtually disappear.
Therefore, claiming that IVF significantly increases the risk of preterm birth is an oversimplification that does not reflect clinical reality.
Factors that may increase the risk in IVF pregnancies
The factors that may increase the risk of preterm birth following IVF are wide-ranging, but most are not related to the in vitro fertilisation technique itself. They are more closely linked to each patient’s medical context:
- Advanced maternal age: women aged over 39 tend to have a higher risk of preterm birth following IVF.
- Cause of infertility: female-related infertility factors, such as endometriosis or polycystic ovary syndrome, can triple the baseline probability of preterm birth.
- Previous conditions, such as endometriosis, uterine abnormalities, thyroid disorders or autoimmune diseases, can also increase the risk of preterm birth.
- Obstetric history: a history of previous preterm birth or recurrent miscarriage is a strong predictor of a further preterm birth.
Factors related to the IVF technique and treatment include:
- Multiple pregnancy: this is the most significant factor, as the likelihood of preterm birth is much higher in multiple pregnancies than in singleton pregnancies. However, today, most assisted reproduction clinics, such as Tambre, opt for single-embryo transfer as standard. This reduces the incidence of multiple pregnancies and the associated risk of preterm birth.
- Fresh versus frozen embryo transfer: IVF cycles using fresh embryo transfer carry a slightly higher risk of preterm birth compared with frozen embryo transfer.
- Egg donation: the use of donor eggs is associated with an increased risk of preterm birth and other obstetric complications compared with the patient’s own eggs.
Impact of multiple pregnancies on risk
One of the factors that has historically had the greatest influence on the risk of preterm birth following IVF has been multiple pregnancy. Twin or triplet pregnancies are, by their nature, more likely to end prematurely. This is because the uterus reaches its maximum capacity much earlier, which can trigger contractions or premature rupture of the membranes. The placenta may also struggle to provide optimal support to more than one foetus throughout the third trimester, which is why labour may need to be induced prematurely.
We must also bear in mind that multiple pregnancies have a much higher incidence of pre-eclampsia and gestational diabetes than singleton pregnancies. These conditions often require doctors to induce labour prematurely for safety reasons.
The figures help to explain why singleton pregnancies are prioritised today:
- Twin pregnancies: the risk of delivery before week 37 is around 60 per cent.
- Triplet pregnancies: virtually 100 per cent of these births are premature, with an average gestational age at birth of around 32 weeks.
Decades ago, the main aim of fertility treatment was to achieve the much-desired pregnancy and, to this end, several embryos were transferred at once, even though this carried the risk of a major complication: multiple pregnancy. Today, this risk has been significantly reduced thanks to single-embryo transfer. With this strategy and new technologies for selecting higher-quality embryos, it is possible to maintain high IVF pregnancy rates without increasing the risk of preterm birth associated with multiple pregnancy.
How to reduce and manage the risk in IVF pregnancies
Given that the risk of preterm birth following IVF depends less on the technique itself and more on each woman’s pre-existing health status and the cause of her infertility, the key lies in identifying and addressing these factors before and during treatment. A preventive and personalised approach helps to reduce the risk of preterm birth in IVF pregnancies, as well as other potential obstetric complications.
At Tambre, this approach to assisted reproduction is an essential part of our clinical practice. Every in vitro fertilisation treatment is designed on the basis of a comprehensive and personalised medical assessment, with the aim not only of achieving pregnancy, but also of helping the pregnancy progress as safely as possible. Our medical team’s expertise and the use of advanced technology enable us to detect, at an early stage, factors that may influence the risk of preterm birth and to take proactive measures.
What the clinic can do to reduce the risk associated with IVF
At centres specialising in assisted reproduction, such as Tambre, we take various measures to reduce the risk of preterm birth following IVF and to support pregnancies reaching term where possible:
- Single-embryo transfer as standard, reducing the risk of multiple pregnancies and their potential consequences.
- Embryo selection. Advances in our understanding of embryonic development and in culture techniques make it possible to identify embryos with the greatest potential for implantation and a favourable pregnancy outcome. Incubators equipped with time-lapse technology, combined with artificial intelligence (AI) algorithms, make it possible to identify embryos with the greatest potential for implantation and development to term without the need for a biopsy.
- Preimplantation Genetic Testing for Aneuploidy (PGT-A). PGT-A analyses whether embryos obtained through IVF have the correct number of chromosomes, known as euploidy. Recent studies show that patients who use PGT-A in conjunction with frozen embryo transfer have lower rates of preterm birth compared with those who do not use it.
- Frozen embryo transfer: evidence also suggests that cryopreservation cycles can provide a uterine environment better suited to embryo implantation, slightly reducing the risk of extreme prematurity compared with fresh transfers.
- Comprehensive pre-treatment assessment of the patient, including coagulation, immunology, thyroid function and vitamin D, among others.
- Treatment of the causes of infertility. Before starting IVF treatment, at Tambre we address, as far as possible, the causes of infertility that may also influence the development of the pregnancy. By optimising each patient’s health — correcting hormonal, metabolic, immunological or uterine abnormalities where possible — we not only improve the chances of treatment success but also help to reduce the risk of preterm birth following IVF.
- Early pregnancy monitoring from week 6 onwards. This enables us to confirm that the pregnancy is progressing normally and to detect, at an early stage, any abnormalities that may increase the risk of preterm birth, facilitating rapid and personalised intervention.
- Assessment of the cervix and the risk of pre-eclampsia during pregnancy — two key factors associated with preterm birth — enabling preventive measures to be taken where necessary.
- Prevention of obstetric complications when risk factors are detected, through specific treatments and monitoring.
Measures implemented at Tambre to reduce the risk of preterm birth following IVF
| Measure | Benefit |
|---|---|
| Single-embryo transfer | Lower risk of multiple pregnancy |
| Advanced embryo selection | Greater safety when transferring a single embryo |
| PGT-A | Lower risk of transferring chromosomally abnormal embryos and of preterm birth in selected cycles |
| Frozen embryo transfer | A more favourable uterine environment |
| Comprehensive pre-treatment medical assessment | Early identification of risks |
| Treatment of the causes of infertility | Improvement of the gestational environment |
| Monitoring from week 6 | Early detection of complications |
If you’re concerned about the risk of preterm birth following IVF or would like to find out more about assisted reproduction treatments, now is the time to get answers to your questions from Tambre’s specialist medical team. You can contact our clinics in Madrid or Alicante to receive information tailored to your specific case and have your situation assessed on an individual basis. Our aim is not only to help you achieve pregnancy, but also to look after your health and the health of the pregnancy and baby.
Frequently asked questions about the risk of preterm birth
1. Why is there talk of preterm birth following IVF if the technique is safe?
Because women who undergo assisted reproduction often have pre-existing factors such as advanced maternal age or certain medical conditions which, in themselves, can increase obstetric risk. This can lead to the perception that IVF increases the risk of preterm birth, when in fact it is not the direct cause.
2. Is the risk of preterm birth the same for all IVF treatments?
No. The risk of preterm birth following IVF varies depending on the patient’s age, previous health, the cause of infertility, whether a fresh or frozen embryo is transferred, and whether it is a singleton or multiple pregnancy. This is why personalised treatment and follow-up are so important.
3. Does transferring a single embryo reduce the risk of preterm birth?
Yes. Single-embryo transfer reduces the risk of multiple pregnancies and, as a result, significantly lowers the risk of preterm birth following IVF, without compromising success rates when embryo selection is carried out effectively.
4. Does the use of donated eggs reduce the risk of preterm birth?
Although egg donation increases pregnancy success rates in older women, some studies suggest that these pregnancies may carry a slightly higher risk of complications such as pre-eclampsia, which sometimes makes it necessary to induce birth early for medical safety reasons.
5. Is it true that all IVF babies are born prematurely?
No, this is not true. In a singleton pregnancy, most babies are born at term. The risk of prematurity increases mainly in multiple pregnancies or when there are additional medical complications, such as placental problems or high blood pressure.