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possible for those couples who would otherwise be unable to have them – a clear majority, but not an overwhelming one.

Yet, for the five thousand or so childless couples who promptly signed up for the new technology, IVF couldn’t have come soon enough. Here was a dramatic addition to the arsenal against infertility, one that could make them parents, even if biology was against them.

Today, assisted reproductive technology, or ART, involves far more than IVF, and includes any procedure in which eggs, sperm, or embryos are manipulated in vitro. Around one in six couples will seek medical assistance because they are having difficulty conceiving a child, and only about one in ten who consult a doctor will go on to use IVF. This is because, though it is probably the most widely discussed reproductive technology, IVF is not the only, or the first, choice when a problem with fertility is diagnosed.

For instance, many couples will turn to induced ovulation, where a woman is treated with hormones to stimulate her ovaries to release eggs. While the ovaries are being manipulated through biochemistry, a couple may conceive merely by timing their sex; they know when the woman’s egg should be triggered for release by the hormone soup she’s taking. That’s much better than guessing.

For couples with unexplained infertility, induced ovulation is sometimes accompanied with intra uterine insemination, or IUI, which can help to get underperforming sperm or eggs in the same place, at the same time. In IUI, semen is first processed in the lab, so that only sperm that are moving can be selected. These ‘good’ – or, at least, somewhat mobile – sperm are then delivered directly into the womb, near where the egg is preparing itself to be fertilized, bypassing the hazards that might assault them in the vagina and cervix, namely, unfavourable pH environment and tricky-to-navigate mucus. The vast majority of sperm are normally killed somewhere en route. Among couples with no clear fertility dysfunction, there seems to be a significantly higher chance of a successful pregnancy when IUI is used with ovarian stimulation rather than on its own, although simply having sex at the right time, which is much easier to pinpoint with ovarian stimulation, might work just as well.

It may also be the case, as with Lesley Brown, that the reason a woman cannot get pregnant is because there is a blockage in her Fallopian tubes, the two passages that connect the ovaries to the womb. If this is the problem, a woman might choose to have surgery to unblock the tubes. But if this fails, or if the woman is already in her mid- to late thirties, when the biological clock is ticking away, IVF may indeed be the best bet.

In IVF, an egg is extracted from a woman and incubated with around fifty thousand sperm. The in vitro part of IVF literally means ‘within glass’, because it originally referred to the fact that the experiments were performed in glassware, which was commonly used in labs instead of plastic. (This is in opposition to ‘in vivo’ fertilization, which comes from the Latin for ‘within the living’.) Fertilization in vitro thus means that the egg and sperm are effectively left to mingle and ‘introduce themselves’ in a specially created, artificial environment, something like a speed-dating night. With the plethora of obstacles in its way safely removed, a sperm can make a direct hit on the egg – as long as it can beat its competitors to it. It follows from the particulars of the set-up that for men whose sperm cannot move properly to the egg or penetrate it to begin fertilization, IVF may simply not work.

By the late 1980s, fertility doctors had found a way to solve this matchmaking problem, without having to resort to donor sperm. Several techniques emerged that could improve an infertile man’s chances of making a baby, with one frontrunner quickly establishing itself: intra-cytoplasmic sperm injection, or ICSI. Like IVF, ICSI does not correct defects in the sperm, but it requires a much smaller number of sperm: instead of fifty thousand sperm, just one will do. ICSI does not leave fertilization to chance. This single sperm – possibly immobile, but otherwise picked for its ‘good looks’ – is first stunned, for example by rubbing its tail. It is next sucked up, tail first, into a sharp-tipped glass pipette and injected directly into an egg. Or, instead of a whole sperm, the doctor can pluck just a single sperm head or nucleus, containing the DNA that provides all the necessary genetic instructions for making a baby – the rest of the sperm is simply a vehicle to get the male DNA into an egg.

Neither IVF nor ICSI are without limitations – their success rates are, at best, only around thirty percent. These remain techniques for assisting natural reproduction, not for replacing it.

But as the use of ART increases worldwide, it is certainly also important to consider some potential long-term consequences. For a start, in both IVF and ICSI, eggs need to be removed from a woman in order to ensure sperm access to them. But eggs are tucked away in the ovaries, and released only infrequently following a biological programme, which makes them far trickier to acquire than sperm. To harvest her eggs, the doctor places the patient under local anaesthetic, and then, guided by ultrasound, passes a long, thin needle through her vagina to the ovaries. The needle is used to suck the fluid out of mature follicles, or egg-containing sacs. If an egg happens to be retrieved with this fluid, it is gingerly removed and tucked into an incubator. And then the process is repeated, until several more eggs join it.

This process of extracting eggs is not just invasive; it carries very real health risks as well. To persuade the

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