Part of our guide: Infertility

The test was positive. A few days later, the hCG level drops, or bleeding starts. In the end, there is a word that sounds technical: chemical pregnancy, or biochemical pregnancy in medical language.

For professional societies, this is no small matter. The European professional society ESHRE expressly counts biochemical losses among pregnancy losses (ESHRE 2022). It is understandable if the loss affects you, even if you knew about the pregnancy for only a few days.

For every number in this article, we state who was studied and how it was counted.

What is a chemical pregnancy?

The international glossary of reproductive medicine (ICMART, 2025 version) describes it as a pregnancy that was detected only through the hormone beta-hCG in blood or urine. It ends before it can be seen on ultrasound. A pregnancy that has been seen on ultrasound, by contrast, is called a clinical pregnancy.

ESHRE classifies biochemical losses as non-visualized pregnancy losses, that is, losses that were never visible on ultrasound. It considers the term “chemical pregnancy” ambiguous (ESHRE 2022). The German-language guideline speaks of a very early miscarriage: the pregnancy is lost before, during, or shortly after implantation with heavier bleeding and can be detected only through an elevated hCG level (AWMF 015-076).

Why doesn't the ultrasound show anything? According to AWMF 015-076, a structure in the uterus should be visible on ultrasound from an hCG level of about 1,500 IU/l, and other publications give values of up to 3,500 IU/l. In biochemical losses, the values measured in studies were far below that, as the section on hCG levels shows.

Signs and what happens

Often there are no specific signs. According to AWMF 015-076, women often perceive a chemical pregnancy as a late period. Without an early test, it often goes unnoticed (Wilcox 1988).

If you test early, you see how it unfolds: a positive test, sometimes only a faint one, followed by weaker or negative tests and bleeding. Based on our research, no study has specifically examined how long this bleeding lasts or which symptoms are typical in biochemical losses. The bleeding durations that guidelines give apply to clinical miscarriages (AWMF 015-076).

Urine tests detect hCG only starting at about 20 to 50 IU/l, while modern blood tests measure values below 1 IU/l. A blood value above 5 IU/l points to a pregnancy. Faintly positive urine tests are easily read as negative, and blood and urine tests are not interchangeable (AWMF 015-076).

After IVF, ICSI, or a frozen embryo transfer, a pregnancy counts as biochemical if hCG was positive and falls again before a pregnancy can be seen on ultrasound. Studies define a positive test at different levels, for example from 3 mIU/ml in Toronto (DiMarco 2026) or from 50 IU/l in at least two tests in Rome (Vaiarelli 2018). 1 mIU/ml equals 1 IU/l. The IVF Due Date Calculator shows when you can test after the transfer.

How common is a chemical pregnancy?

That depends on how early and how sensitively the measurement is made and on what the percentage refers to: all conceptions, all positive tests, or all transfers.

After natural conception

In a US study with daily urine tests, 22% of 198 pregnancies ended before they were recognized clinically (Wilcox 1988, 221 healthy women who wanted to get pregnant). In China, 24.6% of 618 conceptions ended early and 7.9% ended as a clinical miscarriage (Wang 2003, 518 newly married women). For comparison: of the pregnancies recognized clinically, at least 10% to 15% end with an early loss, according to AWMF 015-076.

After IVF, ICSI, and frozen embryo transfer

Study Who was studied Definition and basis of the percentage Biochemical losses
Zeadna 2015, Montreal 1,636 fresh and 188 frozen single embryo transfers, up to age 42 per pregnancy 13.8% fresh, 14.8% frozen
Vaiarelli 2018, Rome 2,451 frozen embryo transfers hCG from 50 IU/l in at least 2 tests, per pregnancy 9.0% to 13.8% depending on the embryo
Muñoz 2024, Spain 3,741 frozen single embryo transfers hCG above 10 IU/l, per transfer 8.2% own eggs, 4.9% egg donation (no significant difference after adjustment)
Ueno 2014, Tokyo 21,882 single transfers of frozen blastocysts, mean age 37.8 years per transfer and per positive test, respectively 7.0% and about 13% (our own calculation)
DiMarco 2026, Toronto 2,443 pregnancies after IVF, including egg donation hCG from 3 mIU/ml, per pregnancy 19.8%

Depending on the positivity threshold and on what the percentage refers to, the proportions were therefore about 5% to 20% (our own summary). Fresh and frozen transfers did not differ (Zeadna 2015). More on this in the article on frozen embryo transfer.

Chemical pregnancies are not more common after IVF than after natural conception. In Montreal, their share after IVF was 14%, compared with 18% in older studies of fertile women. The comparison groups, however, were tested daily with high sensitivity and were younger (mean age 29.4 instead of 34.8 years). The authors conclude: possibly lower, certainly not higher (Zeadna 2015).

Causes: what is known and what is not

The guideline AWMF 015-076 names assumed causes: chromosomal abnormalities of the embryo, implantation disorders, and disorders of the mother's immune tolerance. We did not find any chromosome findings from biochemical losses after natural conception in the literature.

In miscarriages in the first trimester, chromosomal abnormalities are the most common proven cause, found in 50% to 60% according to ASRM (ASRM 2026). As an explanation for biochemical losses, however, they are not enough. After the transfer of blastocysts that tested chromosomally normal (euploid), biochemical losses were not less frequent than after untested embryos: 9.7% versus 9.0% (Vaiarelli 2018) and 8.8% versus 7.5% (Muñoz 2024). Both studies are retrospective and not designed to show equivalence. More on this: preimplantation genetic testing.

And what about progesterone, the hormone of the corpus luteum? For recurrent losses with a luteal phase defect, ESHRE considers the evidence insufficient. With three or more losses and bleeding in the new pregnancy, vaginal progesterone can, according to ESHRE, improve the live birth rate (both are conditional recommendations, ESHRE 2022). The German-language guideline considers progesterone possible for unexplained recurrent miscarriages in the first trimester (a “may” recommendation, AWMF 015-050, 3.10.E62). In Germany, this use is off-label. More on this in the article on luteal phase defect.

hCG levels in a chemical pregnancy

In studies after a transfer, the first hCG values in later biochemical losses were, on average, clearly lower than in later births. The ranges overlap, and the values are not cutoffs.

Study Measurement Later biochemical loss Later birth
Ueno 2014, Tokyo, frozen blastocyst 7 days after transfer Mean 28.7 IU/l (2.1 to 84.6), n = 1,522 Mean 61.1 IU/l (1.3 to 210.2), n = 7,342
Trautner 2024, Linz, day 5 blastocyst 14 days after transfer Median 53 IU/l fresh (n = 10), 55 IU/l frozen (n = 25) Median 931.5 IU/l fresh (n = 186), 1,415.5 IU/l frozen (n = 268)

A low first value is not a definitive verdict. In Toronto, the first value, measured 14 days after fertilization, was at most 50 mIU/ml in 491 of 2,443 pregnancies. Of these, 65.2% ended as biochemical losses, and 12% of the 483 with a known outcome ended with a birth (DiMarco 2026). Fertilio does not evaluate individual lab values; your clinic does that. You will find values for later births by day and type of transfer in the hCG table of the IVF Due Date Calculator.

How quickly does hCG fall after a chemical pregnancy?

We did not find any measurements specifically after biochemical losses. In a US study of 443 women whose pregnancy of unknown location resolved without treatment, hCG fell, depending on the starting value, by 48% to 60% on average in 2 days and by 86% to 94% in 7 days (Butts 2013). The women had symptoms and starting values of up to 10,000 IU/l, so the numbers apply only to a limited extent.

No study has systematically examined when hCG turns negative again. For a pregnancy of unknown location whose hCG falls by more than 50% in 48 hours, the British guideline NICE NG126 recommends a urine test 14 days after the second blood measurement. If it is still positive, a medical evaluation should follow within 24 hours. More on hCG after a loss is in the article Getting pregnant after miscarriage.

How it differs from miscarriage and ectopic pregnancy

Miscarriage: Medical professionals speak of a clinical miscarriage when the pregnancy could be seen on ultrasound. The guideline AWMF 015-076 describes the early loss as a nonviable pregnancy with an empty gestational sac, or an embryo without cardiac activity, in the first 12 weeks after conception. Legally, in Germany a loss under 500 g and before week 24 of pregnancy without signs of life counts as a miscarriage (Family Portal of the German federal government, Familienportal des Bundes).

Ectopic pregnancy: If hCG is positive but no pregnancy can be seen on ultrasound, medical professionals speak of a pregnancy of unknown location. According to AWMF 015-076, 8% to 14% of these later turn out to be a pregnancy outside the uterus. 71% of women with an ectopic pregnancy have hCG values that rise more slowly than in an intact pregnancy or fall more slowly than in a miscarriage. If hCG falls by less than 50% in 48 hours, NICE recommends an evaluation within 24 hours (NICE NG126).

If you have pain or heavy bleeding, get examined by a doctor immediately.

Does it count toward recurrent miscarriage?

That depends on the guideline.

Guideline or glossary Recurrent losses from Do biochemical losses count?
ESHRE 2022 (Europe) 2 pregnancy losses yes, excluding ectopic and molar pregnancies
ASRM 2026 (USA) 2 losses before 22 weeks, not necessarily consecutive yes
SOGC 2025 (Canada) 2 losses, including nonconsecutive ones yes
ICMART glossary 2025 2 clinical pregnancies before 22 weeks no
AWMF 015-050, 2026 (DE, AT, CH) 3 consecutive miscarriages before week 20 of pregnancy (WHO definition) not expressly addressed

A study from Copenhagen of 587 women with unexplained recurrent miscarriages shows why this matters. Non-visualized losses made up 37% of their earlier pregnancies. Each of them reduced the chance of a live birth in the next pregnancy about as much as a clinical miscarriage (relative risk 0.90 versus 0.87) (Kolte 2014).

The German-language guideline recommends an evaluation after three consecutive miscarriages and, in justified cases, even after two (AWMF 015-050, recommendations 2.E1 and 2.E2). This includes, among other things, chromosome testing of both partners if no result from the pregnancy tissue is available, a 3D ultrasound or a hysteroscopy, antiphospholipid antibodies, TSH, and vitamin D. ESHRE recommends the antibody test after as few as two losses, but testing the parents' chromosomes only after an individual risk assessment (ESHRE 2022). If you have had two or more chemical pregnancies, bring it up with your gynecologist or a fertility clinic.

What does it mean for the next attempts?

Woman walking down a bright hallway toward a window in the evening light

With natural conception

In the US study with daily urine tests, 95% of the 40 women with an early loss became clinically pregnant within two years (Wilcox 1988). In China, an early loss was associated with a higher chance of conception in the following cycle, compared with earlier cycles without an early loss (odds ratio 2.6; 1.8 to 3.9). The risk of another early loss, however, was also higher (2.4; 1.4 to 4.2). The early loss was not related to later miscarriages, preterm birth, or low birth weight (Wang 2003). This does not show that women are more fertile afterward.

After IVF and frozen embryo transfer

Study Who was studied After a biochemical loss After a negative test or without implantation
Bates 2002, Boston Women after an unsuccessful IVF attempt ongoing clinical pregnancy in the next cycle 38.4% 27.3%
Yang 2015, Beijing 12,174 first IVF cycles another biochemical loss 7.97%, miscarriage 11.76% 4.01% and 7.41%, respectively
Barrett 2026 2,103 patients, two frozen transfers of euploid embryos in the 2nd transfer biochemical loss 9.9%, clinical loss 10.5% 9.6% and 10.9%, respectively

The clinical pregnancy rate in the next attempt was not lower after a biochemical loss (Bates 2002, Yang 2015). Yang 2015, however, found more repeat losses and regards the biochemical loss as an unfavorable sign; the abstract does not report live births. With euploid embryos, no increased risk of loss was seen (Barrett 2026). The IVF Calculator shows how your chances develop over several attempts.

How long should you wait after a chemical pregnancy?

There is no separate recommendation for chemical pregnancies. After a miscarriage in the first trimester, according to AWMF 015-076, you can try to get pregnant again without delay if there are no individual reasons against it, such as examinations that are still needed or not being emotionally ready (statement 5.S13). That this applies equally to an earlier biochemical loss is our own inference. The US professional society ACOG also sees no good data in favor of delaying (ACOG PB 200).

The WHO recommends an interval of at least 6 months after a miscarriage or abortion. This is based on a single study from Latin America that could not separate spontaneous and induced abortions (WHO 2007). A systematic review of 16 studies and more than one million women found that with an interval of less than 6 months, another miscarriage was in fact less common (relative risk 0.82) (Kangatharan 2017). In the EAGeR trial of 1,083 women after one to two early losses, 53.2% of those who tried again within 3 months had a baby, compared with 36.1% of those who tried later (Schliep 2016, observational data). More on waiting after a miscarriage is in the article Getting pregnant after miscarriage.

After frozen embryo transfer, a new transfer within 6 months after a biochemical or clinical loss was not associated with worse outcomes than one after 6 to 12 months in a cohort of 2,620 women (Yang 2026). There is no guideline recommendation; your clinic sets the timing.

You decide whether you are ready. Trying again soon is possible, but it is not required.

Maternity protection and sick leave

This section applies to Germany, Austria, and Switzerland.

Germany: Maternity protection after a miscarriage has applied since June 1, 2025, from week 13 of pregnancy, lasting 2, 6, or 8 weeks depending on the week (§ 3 para. 5 of the Maternity Protection Act, Mutterschutzgesetz, MuSchG). According to AWMF 015-076, a biochemical pregnancy ends before, during, or shortly after implantation, so long before that. If you are unable to work, your doctor will put you on sick leave. Your employer then continues to pay your salary for up to 6 weeks if the employment relationship has existed for at least 4 weeks (§ 3 of the Continued Remuneration Act, Entgeltfortzahlungsgesetz, EFZG). After that, sickness benefit (Krankengeld) follows (Family Portal).

Austria: There is no protection period. A dismissal is legally invalid up to four weeks after a miscarriage, and the employer can ask for a medical certificate (§ 10 para. 1a of the Austrian Maternity Protection Act, Mutterschutzgesetz, MSchG).

Switzerland: Maternity allowance is paid only if the pregnancy lasted at least 23 weeks (Circular on maternity allowance, KS MSEAE, margin no. 1043). If you are prevented from working through no fault of your own, for example because of illness, the employer continues to pay the wage for a limited time if the employment relationship has lasted more than three months or was entered into for more than three months (Art. 324a of the Code of Obligations, Obligationenrecht, OR).

When should you see a doctor?

Couple sitting close together on the sofa, holding hands

  • Immediately for pain or heavy bleeding. An ectopic pregnancy can also be behind a positive test with no visible pregnancy (AWMF 015-076).
  • If a test does not turn negative again, for example a urine test 14 days after the second blood measurement (NICE NG126).
  • After two or more losses, to talk about an evaluation (ESHRE, ASRM, SOGC, AWMF 015-050).
  • If the loss weighs heavily on you. For women with recurrent miscarriages, the guideline recommends psychosocial support (AWMF 015-050, recommendation 3.6.E34).

If you want a second opinion after several losses, the Fertility Clinic Finder shows you suitable fertility clinics, and all clinics are listed in the clinic directory. The guide to infertility gives an overview of causes and evaluation.

Frequently asked questions

What is a chemical pregnancy?

A pregnancy that was detected only through the hormone hCG in blood or urine and ends before it can be seen on ultrasound (ICMART glossary 2025, ESHRE 2022). ESHRE counts it among pregnancy losses, and the German-language guideline speaks of a very early miscarriage (AWMF 015-076).

How common is a chemical pregnancy?

In studies with daily urine tests, 22% of 198 pregnancies ended before clinical recognition (Wilcox 1988), and 24.6% of 618 conceptions ended early (Wang 2003). After IVF, the proportions were about 5% to 20% of transfers or of positive tests, depending on the study, the positivity threshold, and what the percentage refers to (our own summary).

How do I know if I have a chemical pregnancy?

According to AWMF 015-076, it is often perceived as a late period. If you test, you see a positive test that fades again, and bleeding. We did not find studies on typical symptoms or on the duration of bleeding in biochemical losses.

Is a chemical pregnancy more common after IVF?

Not according to the available data: 14% after IVF single embryo transfer, compared with 18% in older studies of younger fertile women who were tested differently (Zeadna 2015). Fresh and frozen transfers did not differ (13.8% and 14.8%).

Does a chemical pregnancy count as a miscarriage?

For recurrent pregnancy losses, it counts for ESHRE (2022), ASRM (2026), and SOGC (2025). The ICMART glossary counts only clinical pregnancies. The German-language guideline follows the WHO definition of three consecutive miscarriages and does not expressly address biochemical losses (AWMF 015-050).

Am I more fertile after a chemical pregnancy?

The data do not show that. After an early loss, the chance of conception in the following cycle was higher (odds ratio 2.6), but so was the risk of another early loss (2.4) (Wang 2003). After IVF, the clinical pregnancy rate in the next attempt was not lower than after a negative test (Bates 2002, Yang 2015). Yang 2015, however, found repeat losses more often. With euploid embryos, this was not seen (Barrett 2026).

When can I get pregnant again after a chemical pregnancy?

After an early miscarriage, no waiting time is necessary according to AWMF 015-076 if there is no reason against it. For biochemical losses, this is our own inference. After frozen embryo transfer, a new transfer within 6 months was not less favorable than after 6 to 12 months (Yang 2026). Your clinic sets the timing.

Can I get a doctor's note for sick leave after a chemical pregnancy?

Yes, if you are unable to work. In Germany, no maternity protection applies before week 13 of pregnancy. The employer continues to pay your salary for up to 6 weeks if the employment relationship has existed for at least 4 weeks (§ 3 EFZG), followed by sickness benefit (Family Portal).

Sources

Guidelines and glossaries

Studies

Legal sources

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About this article

Fertilio Editorial Team

The Fertilio Editorial Team researches fertility topics using specialist sources such as the German IVF Registry (Deutsches IVF-Register, D.I.R.), medical guidelines, and statutes. The sources are listed at the end of each article. The content does not replace medical advice.