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
Do Women Prefer Large Penises? What the Studies Actually Show
Studies do not reveal one ideal size. Moderate tendencies exist, but preference, perception, and sexual satisfaction are different questions.
Longer or thicker penis: What actually matters during sex?
Small surveys mention girth somewhat more often than length. In practice, arousal, comfort, and how two bodies fit together matter more.
Micropenis: Definition, Measurement, Causes, and What Actually Helps
Diagnosis is based on stretched penile length, age-specific reference values, and the complete clinical picture. Treatment options depend strongly on age and cause.
How to Measure Your Penis: Length, Girth, and Stretched Penile Length
A clear guide to erect length and girth, plus the important difference between those measurements and stretched penile length in a clinical examination.
Latex-free or latex: burning after condom use, what is normal and what is a warning sign?
Burning or itching after condom use is common.
Condom broke or slipped off: what actually matters now
A condom that tears or slips off is a contraception failure and can mean pregnancy risk and a risk of sexually transmitted infections.
Understanding erectile dysfunction: causes, assessment, treatment, and what really helps day to day
Erection problems are common and often treatable.
Sex during pregnancy: safe, flexible, and without pressure
Sex during pregnancy is possible in most uncomplicated pregnancies.
Curious questions about semen: taste, smell, and myths fact-checked
Does pineapple make semen sweeter, can it run out, and does it glow under black light? Curious questions and myths, fact-checked.
Alcohol, Nicotine, Cannabis, Anabolic Steroids and Sugar: What Strains Sperm Quality and Trying to Conceive
When trying to conceive, people often focus on supplements, abstinence days and perfect timing.
Coming too early: What really helps with premature ejaculation and when an assessment makes sense
Premature ejaculation is common, but that does not make it easy to bring up.
Coitus interruptus: effectiveness, risks and what the data really say
Coitus interruptus refers to withdrawing the penis from the vagina shortly before ejaculation so that the ejaculation occurs outside the body. Colloquially this is known as the withdrawal method or "pull‑out". The aim is to keep sperm away from the vaginal area.
Is Homosexuality Inherited? If the Father Is Gay: What Research Shows About Children of Same-Sex Parents
A gay father or lesbian mothers do not automatically make a child gay or lesbian.
Condom sizes: which fits, how to measure, and whether sizes are the same worldwide
A condom should fit snugly without constricting. If it’s too loose, there is a greater risk of shifting or slipping off. If it’s too tight, it often causes pressure, reduced sensation and increased friction, which puts more strain on the material. Many failures may seem like a quality problem but are often, in practice, due to a combination of fit, friction and small user errors.
At-home sperm tests: what do they actually tell you?
At-home sperm tests do exist.
Paternity Test: Process, Accuracy, Consent, and Important Differences by Country
A paternity test can answer important questions, but it is never just a simple DNA comparison.
Understanding porn addiction: when porn and masturbation become a problem
Is very frequent porn use already an addiction? Control and consequences matter most, including effects on relationships, erections, sperm, and trying to conceive.
Immunology in pregnancy: what is actually proven
Online it can sound as though the immune system simply rejects pregnancy and only needs to be calmed down. Medically, it is more nuanced: pregnancy succeeds with a highly regulated immune response. This article explains what is supported by evidence, where diagnostics have limits, and why many immune treatments in fertility care are approached cautiously.
Blood in the urine: common causes, warning signs and next steps
Seeing blood in the urine is alarming, and that's understandable.Blood in semen: causes, warning signs and what to do next
Blood in semen can look alarming, but medically speaking it is often caused by temporary irritation or inflammation.
Pain after sex: common causes, warning signs, and what helps next
Pain after sex is not automatically an emergency, but it is also not something to keep minimizing.
Unexplained infertility: What it means and what comes next after the basic fertility workup
Unexplained infertility does not mean there is no issue.