Biochemical pregnancy: a positive test that doesn’t hold
Biochemical pregnancy: definition, frequency after IVF, causes, whether tests are needed, when to try another transfer, and what it says about your chances.
Read the articleYou’ve probably been told to wait three cycles. This recommendation has never been proven, and recent data actually suggests the opposite.
Around one in five pregnancies ends before the twelfth week, and by far the most common cause is a chromosomal abnormality in the embryo — a random error in chromosome distribution, unrelated to anything you’ve done, eaten or worn. That’s no consolation, but it’s the first thing to know before you start wondering what comes next.
The recommendation to wait three cycles is a tradition, not the conclusion of a study. The available research, including an analysis by the World Health Organisation and several subsequent cohort studies, shows no benefit to waiting. Some studies even show a higher pregnancy rate among those who try again within three months, without any increased risk of a further miscarriage.
The only medical reasons to wait are specific: an infection, a recent dilation and curettage (D&C) with persistent bleeding, hCG levels that have not dropped, or a molar pregnancy, which requires specific monitoring. Apart from these cases, the deciding factor is your own: being ready, not being given the go-ahead.
From a practical point of view, it is helpful to have had one period before trying again, simply to date the next pregnancy correctly.
Periods usually return four to six weeks after the pregnancy ends, or later if the miscarriage occurred at a later stage. Ovulation may occur before these first periods, sometimes as early as the second or third week: it is therefore possible to become pregnant even before your periods return.
The usual practice is to recommend a work-up after two consecutive miscarriages, or sometimes after the first if the woman is over 38, if the pregnancy was at an advanced stage, or if there is a personal or family history of such conditions. This assessment generally includes: karyotyping of both parents, thrombophilia screening and testing for antiphospholipid syndrome, TSH, blood glucose levels, examination of the uterine cavity via hysteroscopy or 3D ultrasound, and analysis of pregnancy tissue if this has been possible. The article on recurrent miscarriages details each test.
In more than half of cases, the results of this assessment are normal. This does not mean the investigation has failed: it confirms that the cause was probably chromosomal and random, which, statistically speaking, is rather reassuring for the future.
After a single miscarriage, the probability of carrying a pregnancy to term remains close to that of the general population, at around 80 per cent. After two miscarriages, it is still around 75 per cent. After three, it is around 65 to 70 per cent with appropriate care. These figures are higher than most couples imagine when they first seek advice.
If the miscarriage occurred after an embryo transfer, two questions arise. Firstly, are there any frozen embryos left? If so, a new transfer can be scheduled as soon as the endometrium is ready and the hCG test is negative – often in the second cycle. Secondly, do we need to change anything? After the age of 38 and two miscarriages, the question of chromosomal testing of embryos becomes a serious consideration, as it specifically rules out the embryos that lead to these losses.
The grief following a pregnancy loss is not proportional to the stage of pregnancy or the number of weeks. Many women tell me they felt they didn’t have the ‘right’ to be devastated over a six-week pregnancy. They do have that right. And whilst resuming the fertility journey in the weeks that follow is medically possible, it is not necessarily psychologically advisable: these two timelines do not always coincide, and it is the latter that must take precedence.
There is no evidence to support waiting for three cycles. Unless there is an infection, persistent bleeding, hCG levels that haven’t dropped or a molar pregnancy, you can try again as soon as you feel ready.
Usually four to six weeks later. Ovulation may occur before your first period returns, sometimes as early as the second or third week: it is possible to become pregnant before your period returns.
Usually after two consecutive miscarriages, or after the first one if you are over 38, if the pregnancy was at an advanced stage, or if you have a history of miscarriages. Fertility returns to normal in more than half of cases.
Around 80 per cent of women carry a pregnancy to term after a single miscarriage, around 75 per cent after two, and 65 to 70 per cent after three, with appropriate care.
Source: https://fertilitegrece.com/en/blog/fertility-after-miscarriage/ — Triada Baloukoudis, IVF patient coordination in Greece. General information, not medical or legal advice. Printed on
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Biochemical pregnancy: definition, frequency after IVF, causes, whether tests are needed, when to try another transfer, and what it says about your chances.
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