What you need to know about DPO

We all are aware that ovulation is the main event in the reproductive cycle of a woman. All the reproductive events like timing baby-making sex etc are dependent on this. It is also the main event that dates a pregnancy and it’s important for every woman to be aware of their Day Post Ovulation.

However, ovulation is a silent internal event, and most women aren’t sure when this actually occurs. They don’t track their cervical mucus/ovulation, and they lose valuable information that their body provides them free of cost every month! In a way, doctors are also to blame; we don’t take either the time or the trouble to teach women how and why their DPO is significant. This is also why most women continue using their last menstrual period (LMP) as the key reference timing milestone and it creates a lot of confusion.

Why the confusion occurs

It's only in women who have a textbook 28-day menstrual cycle in which their ovulation takes place on Day 14. In reality, life is much more unpredictable. It’s why women often have to use some additional tools including ovulation prediction kits, ultrasound scans and BBT charts to pinpoint the day of ovulation.

The primary reason for this confusion is that while the period between ovulation and the next menstrual period (luteal phase) is fairly constant at about 14 days, the length of the time period between the last menstrual period and the ovulation in the present cycle (follicular phase-) can vary considerably from one woman to the next as well as from cycle to cycle.

The significance of calculating DPO right

It’s why the free fertility calculator at can be such a useful tool. When you know how to calculate your DPO (you are able to pinpoint when you ovulate) this is critically important when:

  • You are timing baby-making sex
  • You are dating your pregnancy

This is very important data, especially when you're attempting to figure out whether your pregnancy is healthy or not; it’s also important when your hCG levels & ultrasound scan findings are being interpreted.

Biological age of the embryo

Most women aren’t aware what their DPO is; and that’s why most path lab reports and doctors continue to use the last menstrual period when talking about pregnancy and hCG levels. And so, when your doctor states that you’re 5 weeks pregnant, he is actually referring to the pregnancy’s clinical age- this is the menstrual age, measured from the date of your last menstrual period; it’s not the real biological age of your embryo and this obviously creates a significant amount of confusion. Adding fuel to the fire is the fact that you try to make sense of hCG levels.

The normal ranges for hCG levels are generally printed in the form of the clinical weeks of pregnancy; most reports refer to the completed weeks post the last menstrual period. In fact, this is more so in the case of IVF pregnancies.

The explanation

So, when there is so much of confusion around this, why then isn’t an IVF pregnancy calculated in terms of the date on which the embryo was transferred? And why is DPO still preferred? It’s because some clinics tend to transfer the embryos back on Day 2 while others will do so on Day 5. This is exactly why DPO is much more constant and reliable. Though this isn’t of much consequence in a healthy pregnancy, it can be very important in case the woman has an ectopic pregnancy or a nonviable pregnancy.

Not happy with the attention you are getting from your IVF clinic? Need more information? Please send me your medical details by filling in the form that I can guide you!

Authored by : Dr Aniruddha Malpani, MD and reviewed by Dr Anjali Malpani.