Dutch scientists are working on a radically new form of contraception

Dutch scientists are working on a radically new form of contraception: 'It was not difficult to find female test subjects'

The valve that is inserted into a stent in the fallopian tube, in true size.

A revolutionary new form of contraception: a lock in the fallopian tubes that a woman can open and close at will. Now that the technology is almost finished, clinical research is starting at the Máxima Medical Center in Eindhoven.

Ellen de Visser is science editor of the Volkskrant and writes about health.

May 23, 2025, 09:30

It could well be the ideal form of contraception – reliable, hormone-free, without side effects, passion-proof, always available – and yet the explanation of this new contraceptive initially elicits disbelief. And laughter. A tiny lock in the fallopian tubes, that's the plan, with valves that can open and close. Valves open if you want to get pregnant. Valves closed if you want to remain infertile.

Huh? Do those valves stay closed? Don't the eggs accumulate behind the closed doors? How do you get them open? Doesn't the lock come loose if you fall once? Or have to sneeze hard?

Industrial designer Peter van de Graaf is used to questions and funny remarks. But the contraceptive lock he has been working on with a team of experts for ten years is on the mend. Because the pill, the most popular contraceptive for decades, is under fire: 'pill fatigue' has developed, a growing aversion to the use of hormones, especially among young women.

The use of the contraceptive pill has fallen from 38 to 27 percent in the past decade . One in seven young women now appears to be using a 'natural', unreliable form of contraception, such as an app that allows them to track when they are fertile. The number of abortions has risen sharply in recent years and this could be related to failed contraception, research showed at the end of last year .

First mechanical form of contraception

No, then Choice, as Van de Graaf has named his invention : the first mechanical form of contraception. Locks are applied once (no surgery is required) and then a woman is in control for the rest of her life and decides when she wants children.

After years of technical preparations, clinical research is now being conducted with it, at the Máxima Medical Center (MMC) in Eindhoven.

'It wasn't hard to find women for that,' says Peggy Geomini, a gynecologist at the MMC. 'Many women recognize the dilemmas about contraceptives. This idea appeals to them, they want to help science further.'

'It is a brilliant idea in all its simplicity', says gynaecologist and emeritus professor Bas Veersema (UMC Utrecht) about the contraceptive lock. 'When you see what they have made, it is so small and so clever', says gynaecologist and emeritus professor Marlies Bongers (Maastricht UMC).

'For a long time it was thought that the pill was the solution to contraception, but a growing group of women need an alternative, a non-chemical method.'

Smaller than a pencil point From the suitcase he has taken to an Amsterdam restaurant, Peter van de Graaf takes a prepared fallopian tube in plexiglass. It is a tiny little string: 1.6 millimeters in diameter and 12 centimeters long. It looks so fragile that you wonder how on earth a lock can be placed in it.

But it can. The prototype, built by a German electrical engineering company, is even smaller than a pencil point. Van de Graaf demonstrates the operation in an enlarged model: the valve has the shape of a diagonally stretched letter z. A pull and the valve locks, a push and the valve opens again.

Six years ago, Van de Graaf, who trained at TU Delft, quit his job as a technical lecturer at a university of applied sciences in Zwolle to devote himself entirely to developing the contraceptive method he believes in. Now he has a company with four board members and a board of experts, he works with technicians from TU Eindhoven and searches all over Europe for the right companies for the miniature valves, springs and stents, for the right coatings and a tiny camera. 'Technically, we are 90 percent ready,' he says. Now for the rest.

Unwanted pregnancies

In Europe and North America, where women have good access to contraception, a third of all pregnancies are unwanted, according to a global overview in the journal The Lancet Global Health . Worldwide, this concerns almost half of all pregnancies; each year, 121 million women become pregnant unintentionally, according to figures from the United Nations.

These figures make it clear that women's rights are in a bad state in many countries, but also that contraceptives often fall short. Condoms break, the pill is forgotten and the fertility apps that more and more young women are using give unreliable results. There has recently been a discussion about the IUD because insertion appears to be very painful for some women .

'I realise that the pill has been one of the best inventions for women', says Leonie van de Kamer, who is involved in preparing and setting up clinical research at Choice. 'The pill has allowed me to organise my life the way I have, and I had the choice of when I wanted to have children. For a long time, it was thought that the pill was the solution to contraception, but a growing group of women are in need of an alternative, a non-chemical method.' That alternative has not been developed in the past sixty years, says Van de Kamer: 'I still have the same options as my grandmother.'

Left: the stent, a tube of mesh with two valves and a spring. Right: the tiny endoscope for the fallopian tube. The black dot on the finger is the camera. Lisa van den Berg The fallopian tube as a tunnel

'Plumbing': that is how the technicians described the plan that Peter van de Graaf presented a few years ago: 'Think of the fallopian tube as a tunnel, there has to be something in there that can open and close.' He found the plumbers at companies in France, Germany and England, they are now building the lock that he had in mind.

A minuscule stent is being developed, a tube of mesh with two valves and a spring. This must be placed in the fallopian tube in its entirety. The mechanism that operates the valves is bistable, so comparable to that of a light switch: once the valve is given a push, it falls into the lock without sway. 'Closed is closed, we have tested that', says Van de Graaf. 'Even when we try to spray water through it at high pressure, it doesn't work.'

The two sluices must be inserted by a doctor into the beginning of the fallopian tube and that can be done without surgery, Van de Kamer explains, using a minuscule catheter that is also specially developed. To check whether the stents are in the right place, a miniature endoscope has also been built with a camera and a light that are smaller than a pinhead.

If a woman wants two children, she will have to visit a gynaecologist four times after placement, Van de Kamer explains. That doctor can use a catheter to open the valves and close them again after pregnancy. It is possible that the doctor or perhaps the woman herself will be able to operate the valves remotely in the future: work is being done on a micromotor of 1 by 3 millimetres that can be built into the sluice.

Gynaecologist Marlies Bongers recently tested the tiny endoscope on two women at the Máxima Medical Centre, which will soon be used to check whether the sluices are properly positioned. The camera was not yet completely perfect, says gynaecologist Geomini, who was watching. 'We were not yet able to look into the fallopian tube, we only saw the wall in the lens.'

'Closed is closed, we tested that'

Peter van de Graaf

Placing the first locks

Once the camera has been improved, the big moment will follow: the first sluices will be practiced in the Máxima Medical Center. This will not be done with women who still want to have children, because the method has not yet been adequately tested for this. No, the placement of the sluices will be tested with women whose uterus is being removed. They are participating because they want to help the next generation of women.

They go to the operating room half an hour earlier, so that the gynaecologist can insert the sluices and see how it goes. During the operation that follows immediately, the sluices are removed again. The medical ethics committee has already given permission for this. 'The hospital is enthusiastic, the women themselves too', says Geomini.

The next step is to leave the stents in place for a little longer, so that we can study how the body reacts to them. The idea is to do this with a group of women who will have their uterus removed within three months. Animal research has shown that the stents are well tolerated and that is inevitable, says Van de Graaf, because they are made of nitinol, an alloy of nickel and titanium, which is also used for the stents used in heart patients with narrowed blood vessels.

Build up step by step

Gynaecologist and emeritus professor Bas Veersema contacted Van de Graaf years ago, after reading the first stories about the new contraceptive method. Veersema specialises in sterilisations, knows all the techniques used to close off the fallopian tubes and was keen to help the young company.

That was convenient, because Van de Graaf wants to build up his evidence step by step. When he can start testing the locks on young women in a few years, he wants to start by showing that they do not get pregnant with closed locks. That is in fact a form of sterilization.

'I'm not too worried about the closed valve', says Veersema. 'That will definitely work. Research just has to show whether the stent stays in place.' But what happens when the valve is opened? 'Does the fallopian tube behave as it used to? Does the egg to be fertilized find its way, are there no adhesions or inflammations? That has to be demonstrated first.'

There is, says gynaecologist Marlies Bongers, still a long way to go. Yet she has become increasingly enthusiastic in recent years. 'I initially thought that the idea of ??a lock was too ambitious. A fallopian tube is quite vulnerable. But I am surprised to see what progress has been made.'

Financial gap

How things will continue depends on money. There are tests planned with rabbits, the ideal animals to test the lock: they are quite fertile and their oviducts are relatively easy for researchers to reach. These tests are a prerequisite for being able to test the locks in women in the future. The study is being paid for by the American research financier NIH, which appreciates the Dutch plan.

Then there is a financial gap. Start-ups in medical technology have been struggling for some time now that venture capitalists are dropping out. In the initial phase, there were start-up subsidies for his company, says Van de Graaf, but to get a government subsidy now, he also has to find private investors. They want to see results in the short term, but that is precisely the problem with medical innovations: it also takes a few years for the added value of the contraceptive lock to be demonstrated, let alone that they can be sold soon.

'When we go to companies, within ten minutes we are talking to the managers about their daughters, for whom our contraceptive method might be attractive. So many people get a twinkle in their eyes, except for the financial analysts, who immediately start calculating how quickly they can earn back their investment.'

Choice / Left Peter van de Graaf, middle Leonie van de Kamer, right Peter Vos Lisa van den Berg

Funny questions

They can now answer the funny questions they get about the lock effortlessly. No, no egg cells accumulate behind the flaps, because if an egg cell does not encounter a sperm cell, it falls apart. The remains are cleared away by the body, no route to the outside is needed for that.

And no, if a woman falls hard, the valves do not open. Think of a light switch: it is always on or off and never stays in the middle. The force required to change the position of the valve is so great, says Van de Graaf, that a woman would not survive that.

If Van de Kamer is to judge by the enthusiastic reactions of the young women around her, then that must be the solution for the coming years. The company is looking for 50 thousand women (or men) who are all willing to donate or invest an average of 50 euros. With the 2.5 million that this yields, they can continue their research. 'As a society, we should invest money in this', she says. 'If we don't come up with anything new, we will still be having the same discussion in twenty years.'

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this morning I woke up
and I found the invader.

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