Dear Ma'am, Thank you for your question regarding generic and brand names. The tablet you have been prescribed is called Natural Micronised Progesterone 200 mg often given to women for maintenance of early pregnancy. Hald SR 200 mg is the medication prescribed by your Gynaecologist for this purpose. Tablet Maintaine I believe is a drug called Allylestrenol (5mg),  it is a different salt. It has different sets of indications and contraindications as well as utility. Alternatives to HALD would be: Endogest 200 mg Macgest 200 mg Ultigest 200 mg Her NMP 200 mg Pregcert 200 mg Susten 200 mg. However, I would recommend that you follow the brand advised by your Obstetrician as she may have better experience with the medication prescribed and if difficulty in availability or finance occur with this tablet, consult her for the next best alternative she would prefer. Best Regards, Aditi