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 When Trying for a Baby: How Pressure, Timing and Health Interact
When trying for a baby turns sex into a timed task, closeness can quickly feel like a performance test.
Nominal width of 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, not a diameter and not an obscure laboratory number, but a packaging specification that makes it far easier to compare products 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 fairly straightforward.
Blowjob: Oral sex without pressure – consent, hygiene, protection
A blowjob is oral sex on a penis, and it is only good when everyone involved feels safe and respected.
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 merely a quick lead-in before penetration.
Petting: closeness without sex, understanding risks and setting boundaries
Petting can create closeness 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 be passed on?
STIs from Blowjobs: What the Real Risk Is and How to Protect Yourself
You can catch a sexually transmitted infection from a blowjob.
Can Oral Sex Make You Ill? Cunnilingus and STIs Explained Without the Drama
People often search for getting ill from oral sex or STIs from cunnilingus and hope for a simple answer.
Starting the contraceptive pill: how to choose a formulation and begin safely
The contraceptive pill is hormonal contraception that can prevent pregnancy very reliably when taken correctly.Morning after pill: what to do now, how it works, 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.
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 nearly always comes 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 programme'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 explained
Women are born with a finite ovarian reserve that declines over life.
Signs you’re not getting pregnant: when an assessment makes sense
Clear signs of infertility are rare.
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.
Pregnant from anal sex? What’s possible and how to judge the risk realistically
Anal sex on its own can’t cause pregnancy, because sperm must reach the vagina for fertilisation.
Parentage law in the UK: donor conception, legal parenthood, and what matters in 2026
The UK is much more centralised than the US on donor conception, but that does not mean every route is equally safe.
Maternity notes in the UK: what they contain, how to read them, and what digital access really means
The UK does not use the German Mutterpass, but it does have a very recognisable equivalent: maternity notes, often called handheld notes, pregnancy notes, or increasingly a digital maternity record.
Co-Parenting Across U.S. State Lines: What Changes in Practice and How to Keep It Workable
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. If you are used to a single national family-law system, the U.S. patchwork shows why detailed drafting matters so much. 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: what matters in the first 72 hours
PEP is an emergency medical step after a possible HIV exposure.
How to use a condom properly: a step-by-step guide
A condom works best when you put it on before the first 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 in place.