These are the critical 3 weeks from the point when the hCG test is positive , until you see the heartbeat of your baby on the ultrasound screen.

About the 2WW

A lot has been written about the dreaded two week wait ( 2ww) for infertile couples - the period during which you have to wait to find out whether your infertility treatment has been successful or not. This waiting period is stressful not just for infertile couples, but for everyone trying to conceive - it's the 2ww between testing positive for ovulation using ovulation test kits , and then wondering whether your well timed babymaking sex has resulted in a pregnancy or not .

During this time - whether you've done IUI or IVF or just tried in your bedroom, time itself seems to be in a state of suspended animation . You worry about every little twinge - and you wonder - is this the cycle when we finally make it ? Is this going to be the cycle when I finally get to be a mom ?

As the two week wait drags on and on , you anxiously await the date you need to do your pregnancy test . Many women will do tests way too early, in the hope that they'll see the magic second line ! In this state of hope and confusion , no one can provide you with much useful guidance , because until the test is done, no one can even say what's happening inside your body.

Read more-The 2 week wait and IVF

Critical 3 weeks

Even though the two week wait is a major source of unhappiness, even more important than this 2 week wait is the 3 week wait after your test is positive. These are the critical 3 weeks from the point when the hCG test is positive , until you see the heartbeat of your baby on the ultrasound screen.

While it's true that a lot of two week waits will end up in a negative pregnancy test, the naive assumption seems to be that if the test is positive, all your problems have now ended . This is why when many women get a positive pregnancy test , they are over the moon Unfortunately, this is not true !

Too soon to rejoice

For many infertile women , getting a positive pregnancy test is just the first hurdle . Remember that we want is not just a positive pregnancy test, but a baby - and that's still a long way away! Human reproduction remains an inefficient enterprise , and about 15 percent of all clinical pregnancies will end up in a miscarriage , for no very good rhyme or reason .

However, there's no way of predicting using the pregnancy test as to whether the embryo is viable or not. Even the level of the hCG in the blood test doesn't give us this information . While a high level is more reassuring than a low level, remember that the hCG is produced by the placenta , while what we are looking for is viability of the embryo.

Is the embryo healthy?

While rising HCG levels are reassuring in that they tell us that the placental tissue is multiplying well in utero, they still do not give us any useful information about whether the embryo is healthy or not.
( Though both are part of the pregnancy and are derived from the embryo, the placenta comes from the trophoblast, while the baby comes from the inner cell mass).

Doubling HCG levels tend to lull both doctor and patient into a false sense of security that all is well , but this is not always true. If the heart beat does not appear, this can often be the last straw which breaks the camel's back , and many patients are shattered, because they cannot believe life can be so unfair and unkind.

Random defects

Please do not blame yourself - remember that the commonest reason for a miscarriage is a genetic abnormality in the fetus, and this is Nature's defense mechanism, to prevent the birth of an abnormal baby. While these defects are often random, they are commoner in older women. This is because the eggs of older women have more genetically abnormalities, because they have "aged" and have genetic defects, which cannot be screened for.

A major milestone

Even if your HCG levels are rising well, you now have to wait for the ultrasound scan results , to confirm that your baby has a healthy beating heart. This major milestone occurs between 6-7 weeks of pregnancy - about 3 weeks after your HCG test is positive. The good news is that once a pregnancy test is positive, most pregnancies will be uneventful , and you will end up seeing that glorious strong heartbeat in a few weeks .

Read more-Atlas of ultrasound images during early pregnancy

Seeing your baby's heartbeat can be one of the most emotional and memorable moments in your life - but until you get to this stage , the 3 week waiting period can be extremely difficult to cope with , and there's very little anyone can do to fast-forward time .