Induction of labour

Understanding terms of pregnancy: preterm, full-term, and post-term

January 27, 2025
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Contributors
Veronika Dobiasova, MD
Physician and International Product Manager

Veronika Dobiasova, MD is a physician specializing in obstetrics, gynaecology, and labour induction. She works closely with clinical experts to translate medical evidence into clear, practical information for healthcare professionals and expectant parents.

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Jan Waclav, MD
Clinical & Medical Affairs Director

Physician and Clinical & Medical Affairs Director with 30+ years of experience in clinical research, medical affairs, and evidence-based healthcare. Jan is certified in Anesthesia and Intensive Care Medicine and has held senior medical leadership roles at MEDICEM Technology, SOTIO, GlaxoSmithKline, and AstraZeneca.

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Key takeaways

Preterm, full-term and post-term describe different stages of pregnancy based on how many weeks pregnant you are. Preterm refers to birth before 37 weeks, full-term covers 37 to 42 weeks, and post-term refers to pregnancy continuing beyond 42 weeks.

  • Babies born before 37 weeks are considered preterm and may need additional support depending on how early they are born.
  • Between 37 and 42 weeks, the baby continues to develop and prepare for birth, with 39–40 weeks considered the full-term window.
  • After 42 weeks, the pregnancy is considered post-term and risks may gradually increase as the placenta becomes less effective.
  • Labour induction may be recommended at different stages when giving birth is considered safer for the mother, baby or both.

Pregnancy is a journey full of milestones, excitement, and a fair share of medical terms. Among them, you might hear about preterm, full-term, and post-term pregnancies—phrases that describe how far along your baby is. Understanding these terms can help you feel more prepared for the final weeks of pregnancy and confident in your decisions, especially if labour induction is discussed.

Let’s dive into what’s happening with your baby during each phase and why induction might sometimes be part of the conversation.

What do these terms mean and what’s happening with my baby?

Preterm (before 37 weeks)

Preterm refers to any baby born before 37 weeks of pregnancy. These early weeks are a time of rapid development, but some key systems are still maturing:

  • The lungs are still maturing to support breathing after birth.
  • The brain continues to grow and develop important connections every day.
  • Your baby is also gradually building up fat stores, which will help them stay cozy and maintain their temperature in the outside world.

Babies born very early (before 32 weeks) may need specialized care in a neonatal unit. Late preterm babies (34-36 weeks) often do well but may need support with feeding, temperature regulation, or breathing.

Why might labour be induced early?
Induction during preterm pregnancy is considered only when there’s a medical necessity to deliver the baby sooner than expected, such as:

  • Severe preeclampsia or high blood pressure posing a risk to the mother.
  • Infection, such as chorioamnionitis, that threatens the baby or mother.
  • Growth restriction if the baby isn’t thriving in the womb.

In these cases, the benefits of delivery outweigh the risks of continuing the pregnancy.

image source: DILAPAN-S

Full-term (37 to 42 weeks)

Full-term is the phase most babies aim for. It’s further divided into:

  • Early-term (37-38 weeks): Your baby is likely fully developed, but their brain and lungs are still doing some fine-tuning. Babies born during this time may be slightly more likely to need short-term support, though most thrive.
  • Full-term (39-40 weeks): This is considered the ideal window for delivery. Your baby’s brain is 30% larger than at 35 weeks, and their body has stored enough fat to maintain a healthy temperature outside the womb.
  • Late-term (41-42 weeks): Your baby is fully developed, but the placenta may begin to show signs of aging. Monitoring becomes important during this stage.

Why might labour be induced during full-term?
Induction at full-term is generally recommended if there are concerns about your or your baby’s health, such as:

  • High blood pressure or gestational diabetes that could worsen.
  • Concerns about the placenta’s function, particularly in late-term pregnancies.
  • Ruptured membranes (your water breaking) without labour starting, to reduce the risk of infection.

Post-term (after 42 weeks)

Babies born after 42 weeks are considered post-term. While many babies are perfectly healthy in this phase, the risks increase slightly due to changes in the placenta, which may no longer provide nutrients and oxygen as effectively.

  • Your baby may grow larger, making delivery more challenging.
  • Amniotic fluid levels can decrease, increasing the risk of cord compression.
  • There’s a slight chance of meconium-stained fluid, which could lead to breathing issues at birth.

Why might labour be induced post-term?
Induction is often recommended after 42 weeks to reduce the risk of complications such as:

  • Reduced oxygen or nutrient supply to the baby.
  • Physical challenges during delivery due to a larger baby size.

The bigger picture

Whether your baby arrives early, on time, or a little late, what matters most is their health and yours. Every pregnancy is unique, and induction is just one tool to ensure a safe and positive birth experience when timing or circumstances require it. Pregnancy is full of unknowns, but remember—you’re not alone. Your healthcare team is there to guide and support you through every step, and your body is doing something truly amazing. Take a deep breath, trust the process, and know you’ve got this. 💛

Disclaimer: This blog post is for informational purposes only and should not be considered medical advice. Always consult with your healthcare provider to address your individual needs and concerns.

FAQs
What is induction of labour?

Induction of labour means helping your labour begin with medical support, rather than waiting for it to start on its own. It usually involves preparing your cervix—helping it soften and open—followed by encouraging contractions that work towards a vaginal birth.

What methods are used for labour induction?

Labour induction can involve different approaches, including mechanical and hormonal methods. Mechanical methods help prepare the cervix physically, while hormonal methods use medication to encourage cervical ripening or contractions. The most appropriate method depends on individual pregnancy circumstances and clinical needs.

Can labour be induced after a previous caesarean section?

Yes. Labour induction may be an option for women planning a VBAC (Vaginal Birth After Caesarean). Before induction, the cervix is typically assessed to determine whether cervical ripening is needed. Mechanical cervical ripening methods, such as DILAPAN-S, are commonly used in this setting because they are non-hormonal and may be suitable for women with a previous c-section.

Contributors
Veronika Dobiasova, MD
Physician and International Product Manager

Veronika Dobiasova, MD is a physician specializing in obstetrics, gynaecology, and labour induction. She works closely with clinical experts to translate medical evidence into clear, practical information for healthcare professionals and expectant parents.

Show more
Jan Waclav, MD
Clinical & Medical Affairs Director

Physician and Clinical & Medical Affairs Director with 30+ years of experience in clinical research, medical affairs, and evidence-based healthcare. Jan is certified in Anesthesia and Intensive Care Medicine and has held senior medical leadership roles at MEDICEM Technology, SOTIO, GlaxoSmithKline, and AstraZeneca.

Show more
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