Periods, pregnancy and coming back after birth: what is not known

Every study on jiu-jitsu injuries has a sample that is 88-90% male. A female injury profile, in BJJ, does not exist. That is the starting point everything else on this page follows from.

The menstrual cycle and performance

Here the literature is plentiful and converges on an uncomfortable conclusion. The reference meta-analysis — 78 studies, 1,193 participants — finds a trivial effect of cycle phase on performance, and rates the quality of the evidence as low. The authors write that *general guidelines cannot be formulated* and recommend an individual approach.

A later review on strength is blunter still: it calls it premature to conclude that hormonal fluctuations meaningfully affect performance, and flags a recurring methodological problem — many studies do not actually verify which phase of the cycle the participants are in, assuming 28-day cycles with ovulation in the middle.

The cycle and injury risk

On the anterior cruciate ligament there is a meta-analysis of 68,758 participants: four studies out of five pointed to the luteal phase as the one least associated with injury, but the authors themselves rate the overall strength of the evidence as low, and as very low under the GRADE method. A later review of biomechanical parameters finds four studies out of seven showing no difference between phases, and two pointing the other way: it concludes that the picture is inconclusive, and recommends caution to anyone thinking of changing their training on that basis.

Pregnancy

Here, by contrast, the guidelines are clear and in agreement. The 2019 Canadian guideline, one of the most cited, recommends physical activity in pregnancy — at least 150 minutes a week — and at the same time advises avoiding activities that involve physical contact or a danger of falling, because of the risk of fetal trauma. The examples it gives are horse riding, downhill skiing, hockey and gymnastics. The recommendations of the American College of Obstetricians and Gynecologists point the same way, listing contact sports among those to avoid.

Grappling is never named in these documents — and not because it has been assessed and cleared: because it has never been studied.

Coming back after birth

The 2025 Canadian guideline recommends resuming activity within the first twelve weeks after birth, with gradual, individual progression, and with the criterion of proceeding once any surgical wounds or tears have healed sufficiently and bleeding does not increase with activity. It also flags something useful: routine medical clearance is no longer required, and the “six weeks” rule is not an evidence-based criterion.

Weight cutting

A subject that concerns anyone who competes. The 2023 IOC consensus statement on relative energy deficiency in sport describes what prolonged insufficient energy availability entails: effects on menstrual function, bone health, metabolism, mood and performance. ⚠️ That document, however, does not specifically address weight-category sports, and on prevalence among female jiu-jitsu athletes there is no data at all.

How the categories and the weigh-in work: weight classes.

Why this page is written this way

Because the worst thing we could do is fill the gaps with advice that sounds good. Knowing that a question has no answer is useful information: it tells you the decision has to be made with your doctor and with your own head, not by copying what somebody else did.