HCG Levels After Implantation (When to Test?)

Are you #TTC, in the two-week-wait and have experienced spotting? Could it be implantation bleeding? How long after implantation can you take a pregnancy test? See if your symptoms match signs of implantation and find out about hCG levels after implantation and how soon after implantation your hCG levels might rise to a level detectable by a home pregnancy test.

In this article:

• What is implantation?
• Signs of implantation
• How long after implantation does hCG rise?
• How long after implantation is hCG detected in urine?
• HCG levels after implantation (using study data)
• Comparison chart: HCG levels after implantation
• Summary: How soon after implantation can you take a pregnancy test?

What is implantation?

Implantation is the point of pregnancy where the fertilized egg (embryo) attaches itself to the lining inside the uterus.

Once conception occurs, which happens in one of the fallopian tubes, the embryo has to move down from the fallopian tube into the uterus where it burrows into the soft uterine lining. Shortly after the embryo attaches to the endometrial surface in the uterus, the cells of the placenta begin to form. [1]

Implantation takes place about 6-10 days after ovulation. [2]

You might be able to catch physical signs of implantation happening if you pay close attention to your body.

Signs of implantation

During implantation you may experience mild cramping, abdominal tenderness, and lower back pain. You may also have a brief episode of spotting, known as implantation bleeding.

Implantation bleeding is unlike having a period – the blood is either light in color (almost pinkish) or dark brown, and the flow is very light and short-lived, not enough to soak a sanitary pad. You shouldn’t have painful cramps during implantation as is common with a coming period. [3]

It’s not uncommon to only catch implantation bleeding ONCE when you wipe after going to the bathroom and then not see it again, but some women report having more than one spotting episode following a successful implantation, lasting up to 2-3 days.

By some estimates, up to about 30% of women experience implantation bleeding during pregnancy. It is however possible that this number is in reality higher and many women simply miss the brief instance of spotting as implantation takes place.

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How long after implantation does hCG rise?

The hormone hCG is produced in the body of a pregnant woman almost right away after implantation occurs. It is secreted by the cells surrounding the developing embryo which eventually form the placenta.

HCG levels tend to rise very quickly in early pregnancy, doubling every 72 hours according to the American Pregnancy Association. [4]

Related: Common + Totally Bizarre Early Pregnancy Symptoms

How long after implantation is hCG detected in urine?

HCG finds its way into the urine shortly after implantation.

In fact, there is a close association between the blood and urine hCG levels in pregnancy. The levels and rise of hCG in the urine of pregnant women show a similar pattern to hCG levels in the blood. [5]

HCG levels after implantation

How does hCG rise after implantation, day by day?

If there is one common thing that the #TTC crowd wants to know, it is… How soon can you test after implantation or ovulation???

I have found 2 interesting research papers that I would love to share with you.

We’ll cover each one separately and then COMBINE the data as well.

(1) Johnson, Miro, Barrett, & Ellis, 2009 [6]

This study compares hCG concentrations in the earliest days of pregnancy of 86 women, using a surge in the luteinizing hormone (LH) as a marker. Data is provided for mean, median, and interquartile hCG levels. The interquartile range provides a variety of data while excluding the low and high extremes (the upper and lower quartile values).

Day relative to LH surge	Median hCG levels (mIU/mL)	Q1-Q3 hCG range (mIU/mL)
Day 8	0.00	0.00-0.00
Day 9	0.00	0.00-1.06
Day 10	2.77	1.07-6.98
Day 11	10.15	6.10-18.43
Day 12	21.97	12.79-40.23
Day 13	37.37	20.55-60.75
Day 14	68.37	50.08-104.89

Using the findings in this study I will attempt to portray a pattern at which the hCG levels may rise in the immediate days after implantation to the point of detection on a home pregnancy test. I hope this will help you make sense of day-by-day hCG levels after implantation and understand the earliest time frame to possibly expect a BFP on a home pregnancy test.

As already mentioned, in this study, the hCG concentration is made relative to the days after the LH surge (LH = luteinizing hormone). The LH surge precedes ovulation by about a day or two (28-44 hours). [7,8]

Based on the increased production of hCG in the data provided in this study it seems that implantation had occurred on/by days 9-10 after the LH surge for a significant portion of the participating women. (…Which would be approx. 8-9 DPO (days past ovulation) – considering that LH typically surges a little over a day prior to ovulation, putting ovulation on day 1 after the LH surge.)

• day 1 after the LH surge = ovulation
• day 2 after the LH surge = 1 DPO
• days 9/10 after the LH surge = 8-9 DPO

…Again… this is speculation – For entertainment purposes only!

HOWEVER, the average time frame for implantation to occur is about 8-10 days after ovulation [9], so this is right on track.

Also, the authors of the study note that on day 8 after the LH surge, only 4.8% of women had a value greater than the limit of detection. This climbed to 42.9% on day 9 after the LH surge. (Since DPO would be a day behind, this also supports the assumed timing of implantation.)

Based on the median and interquartile values from this study, hCG levels after implantation could then look something like this:

HCG levels after implantation: median/range (Example #1)

Implantation day: 0 – 1.06 mIU/mL hCG
1 day after implantation: 2.77 mIU/mL hCG (1.07-6.98 mIU/mL)
2 days after implantation: 10.15 mIU/mL hCG (6.10-18.43 mIU/mL)
3 days after implantation: 21.97 mIU/mL hCG (12.79-40.23 mIU/mL)
4 days after implantation: 37.37 mIU/mL hCG (20.55-60.75 mIU/mL)
5 days after implantation: 68.37 mIU/mL hCG (50.08-104.89 mIU/mL)

(Day 6 would be around the time a period might be due if not pregnant. Days after implantation relative to hCG values are estimated and not part of the study.)

Another study I came across presents similar findings.

(2) Gnoth & Johnson, 2014 [10]

This paper provides a reference range for urinary hCG increase in early pregnancy, using a combined cohort data from three different studies conducted over a period of 5 years.

In this summary, duration of pregnancy refers to days since ovulation (unlike days after the LH surge used in the previous study), with ovulation determined as the day of luteinizing hormone (LH) surge + 1 day. Median and 10/90th percentile hCG values are given.

Duration of pregnancy	Median hCG levels (mIU/mL)	10th and 90th percentiles of hCG (mIU/mL)
Day 7	0.00	0.00, 0.20
Day 8	0.06	0.00, 2.91
Day 9	4.04	0.19, 11.32
Day 10	12.23	3.92, 27.01
Day 11	25.04	9.47, 57.82
Day 12	48.10	15.72, 94.09
Day 13	75.25	29.02, 196.95

Let’s do the same thing and use the data from this paper to re-create a pattern of hCG levels after implantation.

Again, in this research paper, duration of pregnancy is calculated by days since ovulation. I’m interpreting the duration of pregnancy as not being inclusive of ovulation, therefore pregnancy day 1 = 1 DPO. Per the authors, ovulation day is determined by LH surge + 1 day (the same I did for the output in the previous study).

Pure speculation on my part again – considering the sudden spike in hCG on pregnancy days 8/9 (8-9 DPO), I would assume that’s when implantation had occurred for most women that participated in these studies. So far this is consistent with the previous study and with the average time frame for implantation in general, which is 8-10 days after ovulation [9].

Using the median and 10/90 percentile values, day-by-day hCG levels after implantation would be as follows:

HCG levels after implantation: median/range (Example #2)

Implantation day: 0 – 2.91 mIU/mL hCG
1 day after implantation: 4.04 mIU/mL hCG (0.19-11.32 mIU/mL)
2 days after implantation: 12.23 mIU/mL hCG (3.92-27.01 mIU/mL)
3 days after implantation: 25.04 mIU/mL hCG (9.47-57.82 mIU/mL)
4 days after implantation: 48.10 mIU/mL hCG (15.72-94.09 mIU/mL)
5 days after implantation: 75.25 mIU/mL hCG (29.02-196.95 mIU/mL)

(Day 6 would be around the time a period might be due if not pregnant. Days after implantation relative to hCG values are estimated and not part of the study.)

Now, let’s compare the data from both studies so that you can see the hCG levels after implantation side by side.

Comparison chart: HCG levels after implantation

• Median hCG values originate from the two studies discussed above [6,10].
• The hCG range (lower/higher) is a combination of the data from both studies.
• Correlation to days after implantation is an estimate based upon the data provided in these two studies.

This is an example of how hCG can build up in your system in the immediate days following implantation:

	Median hCG [6]	Median hCG [10]	Lower range combined hCG	Higher range combined hCG
Implantation day	0 – 1.06	0 – 2.91	0 – 1.06	1.06-2.91
1 day after implantation	2.77	4.04	0.19-1.07	6.98-11.32
2 days after implantation	10.15	12.23	3.92-6.10	18.43-27.01
3 days after implantation	21.97	25.04	9.47-12.79	40.23-57.82
4 days after implantation	37.37	48.10	15.72-20.55	60.75-94.09
5 days after implantation	68.37	75.25	29.02-50.08	104.89-196.95
6 days after implantation	121.92	137.19	45.06-71.04	175.92-301.08

Interestingly, based on these studies, the rate of hCG increase immediately after implantation appears to be FASTER than what is typically given for early pregnancy in general (hCG doubling every 2-3 days).

The authors of the first study (Johnson, Miro, Barrett, & Ellis, 2009, [6]) do make a note of that:

“There was a 30-fold increase in mean urinary hCG between days 8 and 9 after the LH surge, a 5-fold increase between days 9 and 10, a nearly 3-fold increase between days 10 and 11, doubling between days 11 and 12, and a slower rate of increase in the days that followed.” [6]

(Note: The authors were summarizing the mean hCG rate as opposed to the median hCG rate that we have gone over. While the median values remain at 0 hCG at first, there is a clear initial rapid rise in hCG that slows down thereafter in the median values as well.)

Another study publishes similar findings:

“Daily mean urinary hCG concentrations rose rapidly, with daily increases ranging from an initial 3-fold rise to a 1.6-fold rise by the end of the week. In summary, maternal urinary hCG levels are quite variable during the first week following implantation. During this gestational stage, hCG patterns rise very rapidly but the relative rate of rise decelerates as the week advances.” [11]

Days	Rates of increase (Mean)	10 percentile	90 percentile
1–2	3	1.3	7.1
2–3	2.3	1.1	5.3
3–4	2.3	1.0	6.2
4–5	2.1	0.9	5.9
5–6	2.0	0.9	5.3
6–7	1.6	0.8	3.6

How soon after implantation can you take a pregnancy test?

(… and see a BFP if you are pregnant?)

How soon you’ll get a positive result on your pregnancy test will depend on the levels of hCG in your system and the kind of test you use. Different pregnancy tests are able to detect varying amounts of hCG in the urine and can produce different results.

If you’re using a very sensitive test (like this one from First Response), you should wait about 2 days until you test after suspected implantation.

Wait at least 3-5 days after implantation if you’re not sure about the detection threshold of your home pregnancy test to avoid getting a false negative.

Can you test positive 24 hours after suspected implantation? It’s unlikely that you would. At only a day following implantation, your hCG levels would likely still be too low for even the most sensitive home pregnancy tests to register. Unless implantation happened earlier than you had estimated… which is, of course, possible.

The bottom line is, at the very minimum, you should wait at least 2 days after the signs of implantation to up your chances of getting a BFP, ideally using some of the most sensitive pregnancy tests like this one with a presumed analytical sensitivity of approx. 6.3 mIU/mL [12] – that is an extremely low hCG level! (With this pregnancy test you will only need hCG levels of 6.3 mIU/mL or higher to trigger a positive result. The average pregnancy test detects around 20-25 mIU/mL of hCG – meaning you will have to have hCG concentrations of at least 20-25 mIU/mL in order to get a positive result, and some brands go up to 40-50 mIU/mL.)

Notice in the hCG levels after implantation charts posted above how soon you could get a BFP with a pregnancy test sensitivity of 6.3 mIU/mL VS. 20-25 mIU/mL or even higher. There could be a delay of several days. It’s perfectly fine to use *any* kind of commercial pregnancy test as long as you’re aware that some produce earlier results.

Either way, the levels of hCG after implantation as much as triple initially, so if you are pregnant it shouldn’t take very long for a pregnancy test to register.

Fun fact: Women expecting multiples tend to have higher hCG levels than women with a singleton pregnancy.

When testing shortly after implantation, before your period is due, your first morning urine is bound to give you the most accurate results. First morning urine is more concentrated, which means more hCG and a higher likelihood of getting a BFP.

Baby dust, my friend! 🙂

Related:

• 7 Common Prenatal Vitamin Myths to Read About
• How To Choose the Best Prenatal Vitamins for Your Pregnancy
• Common (+Totally Bizarre) Early Pregnancy Symptoms

References:

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1. UCSF Health; Conception: How It Works. [UCSF]
2. Implantation and Establishment of Pregnancy in Human and Nonhuman Primates; Ren-Wei Su, Asgerally T. Fazleabas; Adv Anat Embryol Cell Biol. 2015; 216: 189–213. [NCBI]
3. Healthline; Implantation Signs. [Healthline]
4. American Pregnancy Association: What is hCG? [APA]
5. Relationship between blood and urine concentrations of intact human chorionic gonadotropin and its free subunits in early pregnancy; R J Norman, M Menabawey, C Lowings, R H Buck, T Chard; Obstet Gynecol. 1987 Apr;69(4):590-3. [PubMed]
6. Levels of urinary human chorionic gonadotrophin (hCG) following conception and variability of menstrual cycle length in a cohort of women attempting to conceive; Sarah R Johnson, Fernando Miro, Sophie Barrett, Jayne E Ellis; Curr Med Res Opin. 2009 Mar;25(3):741-8. [PubMed]
7. Ovulation detection in the human; J Kerin; Clin Reprod Fertil. 1982 Mar;1(1):27-54. [PubMed]
8. Detection of ovulation, a review of currently available methods; Hsiu‐Wei Su, Yu‐Chiao Yi, Ting‐Yen Wei, Ting‐Chang Chang, Chao‐Min Cheng; Bioeng Transl Med. 2017 Sep; 2(3): 238–246. [NCBI]
9. Time of implantation of the conceptus and loss of pregnancy; A J Wilcox, D D Baird, C R Weinberg; N Engl J Med. 1999 Jun 10;340(23):1796-9. [PubMed]
10. Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments; C. Gnoth and S. Johnson; Geburtshilfe Frauenheilkd. 2014 Jul; 74(7): 661–669. [NCBI]
11. Urinary hCG patterns during the week following implantation; PA Nepomnaschy, CR Weinberg, AJ Wilcox, DD Baird; Hum Reprod. 2008 Feb; 23(2): 271–277. [NCBI]
12. Sensitivity of over-the-counter pregnancy tests: comparison of utility and marketing messages; Laurence A Cole, Jaime M Sutton-Riley, Sarah A Khanlian, Marianna Borkovskaya, Brittany B Rayburn, William F Rayburn; J Am Pharm Assoc (2003). Sep-Oct 2005;45(5):608-15. [PubMed]

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