10-Magnesium/Calcium
There is anecdotal evidence that taking these two in combination can increase the risk of twins (although you should check dosage with your doctor/chemist). It may also increase the chance of having girls.
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11-Stopping Birth Control
If you’ve been on hormonal birth control for six months or longer and stop, it can take several cycles before the body adjusts to the change. This can increase hormone levels and the chances of multiple eggs dropping.
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12-Maca Root
A Peruvian fertility treatment that appears to increase the chance of twins. Side effects may include mood swings and other issues, so make sure you do your research and correctly dose if you’re planning to try this.
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13-Pineapple Core
The core of the pineapple contains the highest concentrations of bromelain, which anecdotally is supposed to increase the chances of implantation following ovulation. However, it’s also associated with contractions and miscarriage with over use, so should be used with care and your own research. It can be taken in raw form or pill form.