8 DPO: The Most Common Implantation Days Begin

Eight days past ovulation is when the most common implantation window opens. For many pregnancies, the embryo is settling into the uterine lining around now and beginning to send its first hormonal signal. That signal starts tiny. This page explains what happens at 8 DPO, how quickly hCG builds after implantation, and what that means for testing.

What happens at 8 DPO

If there is a blastocyst, it has hatched and is ready to attach. Attachment begins around 6 days after fertilization, and the MSD Manual says implantation is completed by day 9 or 10.⁶ In the NIH study of 221 women who collected daily urine, 84% of continuing pregnancies implanted on day 8, 9 or 10 after ovulation.¹

As the outer layer of the embryo, the future placenta, burrows into the lining, it starts releasing hCG. That hormone keeps the corpus luteum going, so progesterone keeps flowing instead of falling before a period, and it is what pregnancy tests detect.⁷

8 DPO and implantation

Implantation is a quiet process. In the same study population, researchers looked at bleeding in 151 clinical pregnancies. Just 9% had any bleeding in the first 8 weeks; it tended to come around the time of the expected period and rarely on the day of implantation.⁴ They found no support for the hypothesis that implantation causes vaginal bleeding.⁴ Our pages on implantation bleeding and what implantation bleeding looks like go into detail.

Cramping at 8 DPO is similar: common, usually harmless, and not a reliable signal either way.

8 DPO symptoms

Progesterone peaked over the last couple of days, so breast tenderness, bloating and tiredness are still likely, pregnant or not. Even with implantation under way, hCG at 8 DPO is so low that it is unlikely to cause symptoms of its own.

How fast hCG rises after implantation

Once hCG appears, it rises fast. A study of 142 naturally conceived pregnancies measured hCG in first-morning urine for the week after it was first detected:²

By the seventh day, the average level was more than 100 times higher than on the first day.² The study also found high variability between pregnancies, and implantation after day 10 was linked with slower rises.²

Can you get a positive pregnancy test at 8 DPO?

Rarely. In daily urine samples from 109 women who conceived, median hCG at 8 DPO was 0.06 mIU/mL, and 90% of pregnancies were below 2.91 mIU/mL.³ For comparison, the most sensitive home tests in a 2011 lab study detected about 5.5 mIU/mL, and many others needed about 22 mIU/mL.⁵ So at 8 DPO, even a very sensitive test will be negative in the large majority of pregnancies. An 8 DPO negative is expected and is not a sign the cycle has failed.

If you do plan to test before your period, sensitivity is the feature that matters most.

What to do now

Give hCG two or three more days. The table above shows why: two days of a threefold and a twofold rise can lift a level from undetectable to detectable. Our DPO calculator shows your dates, and our guide on how many days after ovulation you can test sets out the odds by day.

Match the test to the timing. Early-detection tests make sense before your period is due; lower-cost strips are fine once it is due.

Look after yourself. See coping with the two-week wait. Next: 9 DPO, the median day of implantation. If this cycle is not the one, track smarter next time.