Philipp Marx
Founder of RattleStork
Philipp Marx is a founder of RattleStork and a former international sperm donor. He writes from first-hand experience about sperm donation, co-parenting, and alternative paths to parenthood.
Before founding RattleStork, Philipp donated sperm in several countries. That experience showed him how differently people approach donor conception, trust, personal boundaries, and co-parenting.
At RattleStork, he combines that perspective with publicly available sources and practical guidance for donors, recipients, and prospective co-parents. His personal experience is not a substitute for medical or legal advice.
Articles by this author
Total published articles:220
Erection Problems During Family Planning: How Pressure, Timing and Health Interact
When family planning turns sex into a timed task, closeness can quickly feel like a performance test.
Nominal width for condoms: meaning, conversion, and how to find the right size without a calculator
The nominal width is a measurement in millimetres that describes the width of a condom when laid flat. It is not a body-width measurement, not a diameter, and not a secret laboratory number; it is an indication on the packaging that allows products to be compared far more reliably than labels such as "Standard", "Regular", "Large" or "XL".
Swallowing semen: healthy or risky? STI risk, pregnancy and clear answers
Swallowing semen can feel like an awkward question, but medically it is usually quite straightforward.
Blowjob: Oral sex performed on men explained clearly
A blowjob is oral sex performed on a penis. For some couples it is a pleasurable part of their sexuality; for others it feels uncomfortable or simply does not suit them. Both are normal.
Cunnilingus: Oral Sex on Women Explained Clearly and Realistically
Cunnilingus, often simply called going down on someone, means oral sex on the vulva.
Foreplay: ideas, communication, desire and safety without performance pressure
Foreplay is not just a quick lead-in before penetration.
Petting: Intimacy without sex, understanding risks and respecting boundaries
Petting can create intimacy without penetration, but it often brings up the same questions: what counts, where are the boundaries, when does pregnancy risk become real, and which sexually transmitted infections can still spread?
STIs from Blowjobs: What the Risk Really Is and How to Protect Yourself
A blowjob can transmit a sexually transmitted infection.
Can Oral Sex Make You Unwell? Cunnilingus and STI Risk Explained Clearly
Many people search for getting unwell from oral sex or sexually transmitted infections from cunnilingus and hope for a simple answer.
Starting the contraceptive pill: how to choose a formulation and get started safely
The contraceptive pill is hormonal contraception that can prevent pregnancy very reliably when taken correctly.Emergency contraception: morning after pill, what to do now, and when to test
The morning after pill is emergency contraception after unprotected sex or a contraception accident.
How much semen does it take to get pregnant?
In theory, a single sperm cell is enough to fertilise an egg. In practice, the fertile window, motility and the journey to the egg decide the odds, and what actually changes with a drop, semen on the outside, consistency, and ICI, IUI, IVF and ICSI.
Am I Too Old to Be a Sperm Donor? What Age Limits Really Mean
If you are thinking about sperm donation and you are no longer in your early 20s, the same question usually comes up first: am I already too old for this? The honest answer is neither a simple yes nor a simple no. There is no magic number that applies everywhere. What matters is a program's internal age limit, your screening, and whether your profile still makes medical and practical sense for donor selection.
How many eggs does a woman have? Ovarian reserve, ovulation, and age in plain language
Women are born with a finite ovarian reserve that declines over life. Here you will get a clear orientation on typical orders of magnitude, ovulation, tests such as AMH and antral follicle count, and what age means for egg quality.
Signs you’re not getting pregnant: when to consider a check-up
Clear signs of infertility are rare. Often, you only notice it because pregnancy doesn’t happen despite regular attempts. In this article you’ll learn common clues related to your cycle, pain, and sperm, when medical evaluation is recommended, and what next steps can actually help.
Hymen: what it really is and why it proves nothing
Many people look for information about the hymen, also called the vaginal corona, and wonder whether you can tell virginity from it or whether it always tears and bleeds the first time you have sex. Here you will learn what is medically true, which myths persist, and when pain or bleeding should be checked.
Pregnant from anal sex? What’s possible and how to assess the risk calmly
Anal sex by itself can’t cause pregnancy, because sperm must reach the vagina to fertilize an egg. Risk only exists if semen gets onto the vulva or into the vagina. Here you’ll learn how to think about emergency contraception and when a test can give reliable clarity.
Parentage law in India: donor conception, ART regulation, and what matters in 2026
India does not approach donor conception through a broad, queer-family parentage model.
Pregnancy records in India: MCP card, antenatal notes, and what really matters in 2026
India does not use the German Mutterpass, but it does have close equivalents that matter a great deal in real antenatal care.
Co-Parenting Across U.S. State Lines: What Changes, What Stays the Same, and How to Keep It Practical
Living in different states does not automatically make co-parenting fail, but it does raise the stakes. Parentage, decision-making, travel, money, and relocation all need clearer rules when a plan has to work across state lines. For readers outside the U.S., this is a useful example of how jurisdiction can shape family-law drafting in practical ways. This guide focuses on the pressure points that usually break a weak agreement and the defaults that make a long-distance plan easier to live with.
PEP after a possible HIV exposure: the first 72 hours matter most
PEP is an emergency medical step after a possible HIV exposure.
How to use a condom correctly: a clear step-by-step guide
A condom works best when you put it on before any direct contact, leave room at the tip, roll it all the way down, and remove it carefully afterwards. The steps are simple, but the small details decide safety, comfort, and whether it stays on.