This is a very controversial issue. The existence of genital bleeding in the first trimester of pregnancy is very common. During this period, contact between the maternal blood and the embryonic structures occurs once the gestational sac is incorporated into the inner wall of the uterus (endometrium).

The embryo remains in the fallopian tube for several days and it is not until a week after fertilisation that implantation occurs inside the uterus. Once there, a series of changes occur that will generate a blood supply from the mother that provides energy to the embryo that is starting to develop.

When implantation occurs, bleeding is never usually noticed, because as we said before, implantation occurs around day 20-22 of the cycle, that is, one week after ovulation and fertilisation and one week before expected menstruation.

Bleeding usually begins one week after implantation, i.e. around the expected date of the period or even after the pregnancy is detected by a urine test.

There are some ultrasensitive pregnancy tests that detect very small amounts of human chorionic gonadotropin (hCG) that occur 2 to 4 days after implantation, that is, about 3-5 days before the expected period date.

These post-implantation bleeds are similar to bleeding that occurs with any hormonal oscillation (usually a temporary drop in progesterone levels). In threatened miscarriages, therefore, they are not easy to interpret and should be treated with a course of progesterone (which may be missing) and physical rest to lower blood pressure and close off the blood vessels that are draining the blood outside.

Because assisted reproduction treatment are hormonal, patients may feel changes in their body. These do not happen to all women equally and usually disappear at the end of the treatment. The most common discomfort can be: slight swelling of the chest and abdomen, fatigue, mild headache, mood swings, constipation, nausea, tachycardia, and fluid retention.

The local effect of the medication administered subcutaneously may be swelling, redness, and itching of the area that usually disappears on the same day or 2 days after administration.

Many patients believe that in IVF it is difficult to avoid multiple pregnancies, and this is inaccurate. The occurrence of a multiple pregnancy depends exclusively on the number of embryos that reach the uterus during the woman’s fertile period. In assisted reproduction treatments, transferring more than one embryo per attempt is largely avoided nowadays. In artificial insemination it is not so easy to control the number of embryos because the technique does not use embryos but rather sperm. However, in IVF, it is the woman (on the advice of her gynaecologist) who decides the number of embryos to use; therefore, the risk of multiple pregnancies is more controlled in IVF than in artificial insemination.

A common question for women considering IVF is how many eggs will I lose in the future if I undergo IVF treatment?

If you are concerned that a higher than “normal” egg usage could cause a disorder, a health problem or bring your menopause forward, you rest easy, because in an IVF treatment no egg is lost that could be useful in the future.

How is this possible? You thought that every month a single egg is used, and in a stimulation a few dozen eggs can be extracted from the ovary. You had also heard that if you first got your first period at a younger age, you would also get the menopause at a younger age.

This idea was understood to be true a few decades ago, but it is a false interpretation. If this were true, a woman who has multiple consecutive pregnancies, or if she takes the contraceptive pill for many years, would use hardly any eggs, and would get the menopause several years later and yet this does not happen.

Menopause comes regardless of whether a woman ovulates every month or not. Ovulation is not the source of egg loss; ovulation allows one of the thousands of eggs that are inevitably used each month to “taken advantage of” (to achieve pregnancy), and this use of eggs has no relation to ovulation.

A 20-week-old female foetus has more than 6 million eggs inside her ovaries. However by the time she is born, she has already lost 5 million eggs, so at birth, she would have approximately 1 million eggs, that is to say, she only retains 16% of the eggs that she had 20 weeks before then.

By the time this girl gets her first period, she only has around 350,000 eggs in her ovaries, of which just over 400 eggs will ever reach the fallopian tube with ovulation. What about the rest of the eggs? Where do those 6 million eggs that do not ovulate go?

Those eggs degenerate (atresia), they die. This happens continuously and today there is no way to prevent them from being lost. That is why we are not worried when these eggs are used in an IVF treatment, since these eggs were destined to be lost every month. More than 2000 eggs are lost every month from birth. When a girl gets her first period, one of these eggs leaves the ovary to mature and can be used to achieve pregnancy. However the rest are lost, and there is nothing we can do to avoid it. When hormonal stimulation is performed, up to 10% of the eggs consumed in that cycle can mature, more than 90% of the amount consumed that month cannot be used.

In the period of maximum fertility (between the age of 20 and 30), 96% of a woman’s eggs have already been consumed, but she still has around 250,000 eggs in the ovaries that disappear almost entirely with the menopause, when just under 1000 eggs are still preserved.