Final answer:
To lower risk to a fertilized ovum, the mother should abstain from harmful substances especially during the first eight weeks. In clinical settings, careful handling and transfer of embryos reduce risks. Long-term prevention may involve sterilization or hormonal contraceptives.
Step-by-step explanation:
Reducing risk to a recently fertilized ovum involves several measures, most notably avoiding exposure to harmful substances that could compromise the embryo's proper development. To ensure the health and safety of the fertilized egg, the mother should abstain from alcohol, illegal drugs, and some medicines, particularly during the critical first eight weeks post-fertilization when major organ formation occurs. In medical scenarios like in vitro fertilization, maintaining the eggs in physiological conditions in the laboratory, followed by their transfer to the uterus at an optimal time, is also crucial to reduce risks. It might also be advisable to use progesterone to help prepare the uterus to support a pregnancy after egg retrieval.
In the broader context of fertility awareness, avoiding unprotected sex during the most fertile periods of the menstrual cycle, unless pregnancy is desired, can reduce the risk to a fertilized ovum. Moreover, long-term solutions include sterilization procedures such as vasectomy, tubal ligation, or the implantation of hormonal contraceptives, which have shown to greatly diminish the chances of fertilization.
Nevertheless, to effectively reduce the risks to a fertilized ovum, both short-term precautionary measures and possible long-term decisions must be taken into account, always in consultation with a healthcare provider.