It’s true that there are many members of House Targaryen who suffered from fertility issues, but I’m uncertain if its a case of it affecting the house as a whole, or if its each character having their own unique situation, so lets do an analysis. The Targs/Targ-blooded/Targ married characters known to have (rumored in some cases) suffered from fertility issues are Aegon I, Visenya, Maegor, Alyssa Velaryon, Alysanne, Alyssa Targaryen, Daella, Aemma Arryn, Laena Velaryon, Rhaenyra, Rhaena, Naerys, Kiera of Tyrosh, Rhaella and Daenerys. In hindsight, this isn’t actually that big of an amount, considering just how many members of house Targaryen there are, I expected more members to have known fertility issues with how often ppl discuss the Targ family’s fertility problems. If we examine each case it gets even more unlikely that the family has an actual fertility problem, as each one is sorta unique.

Aegon I and Visenya - While it did take awhile, they did eventually produce a healthy child together. Sure there were rumors of one or the other being infertile, and that Maegor might be a blood magic baby, but at the end of the day that’s all it is, rumors. There’s no proof that either is infertile, especially in Aegon’s case with Aenys’ added existence, (unless you want to believe those rumors about Rhaenys), and its very likely these rumors were simply stirred up to slander the conquerors.

Maegor - Oh man, Maegor, where do I even begin with him? There’s a multitude of reason as to why this guy struggled to conceive but I don’t think it has anything to do with an innate fertility issue with house Targ. It could be curse related, whether due to the involvement of blood magic on Visenya’s end, or Tyanna’s involvement when he was comatose. But I don’t actually think Maegor was infertile, the fact that he could even get his wives pregnant was evidence that he had some fertility. I think the loss of his children were more than likely due to Tyanna’s involvement with her likely poisoning/cursing the children rather than Maegor himself.

Alyssa Velaryon and Alysanne - Alyssa dying in the child bed and Alysanne’s rough labors/dying infants (Gaemon and Valerion) are more than likely due to their pregnancies happening so late in their lives. Pregnancies in older women are often at high risk of complications, so the culprit here is old age not innate poor fertility.

Alyssa Targaryen and Laena Velaryon - This is where things get a little strange, as both Alyssa and Laena were healthy, young women who’d produce two healthy children in prior pregnancies, only to suffer complications on their third child. An act of nature? Perhaps. Unless you believe in the great maester conspiracy theory.

Daella and Aemma Arryn - Mother and daughter both gave birth incredibly young, Daella dying as a result and Aemma suffering from countless miscarriages and stillbirths, with only Rhaenyra as her surviving child. In their case, there is a chance their fertility issues were caused by enduring pregnancy at such a young age, but they also fall under the suspicion of maester conspiracy, especially Aemma.

Rhaenyra - Queen Rhae’s miscarriage was definitely stress induced and not due to poor fertility, stress and despair is what caused her tragic loss, this is an extremely unique case.

Rhaena and Kiera - Rhaena suffered a miscarriage, but the details are uncertain. Potential victim of the maester conspiracy? Or just nature? Kiera is also similar, she suffered a miscarriage of twins, which could be a natural occurance, though there is rumors of black magic being used to trigger the miscarriage, possibly at the hands of Bloodraven.

Naerys and Rhaella - Naerys was known to have a sickly, delicate disposition, so that may explain her struggles with birth and eventual death on the childbed. As for Rhaella, she suffered many, many stillbirths/lost children, and eventually succumbed to the child bed, but I don’t believe she was ever mentioned as having a particularly weak consitition. Maybe she did, or maybe she was simply healthy but infertile. Once again, a potential victim to maester conspiracy.

Daenerys - Incredibly unique circumstances, her childloss was the result of the cursework of a maegi, but she may not be infertile like she thinks she is. In her last chapter in A Dance With Dragons, there’s the potential implication of a miscarriage, likely stress induced, similar to Rhaenyra.

So what is my conclusion? Honestly, idk, I’m not inclined to believe house Targaryen suffers from any unique, genetic fertility dilemma, in fact, there are plenty members of House Targaryen that prove the opposite by having, like, a bajillion kids (looking at u Aegon IV). I think some characters may have struggled with fertility, but it was an issue unique to them rather than a condition that plagued their house, cuz honestly most of these infertility issues have genuine explanations (old age, stress, poisoning, etc.) In the case of characters like Daella, Aemma, Laena, Alyssa Targaryen, or even Kiera of Tyrosh, I could see their fertility issues as being caused by the maesters of the Citadel, especially the women who died in child birth prior to the dance. I wouldn’t be surprised if there was foul play involved with the maester’s intentionally trying to poison and harm house Targaryen’s lineage. In Kiera’s case, her miscarriage could also be the result of Bloodraven’s meddling. Ultimately, I feel that house Targaryen doesn’t have natural fertility issues, but perhaps fertility issues that are being caused by the harmful scheming of those whom wish to see their collapse from power. As for my dragonlord family, no, House Calaerys doesn’t really suffer from fertility issues and Saerea’s mother’s passing was a unique, unexpected case.