Sayyed Mohammad Al-Musawi, Sayyed Mohammad al-Musawi is originally from Iraq and heads up the World Ahlul Bayt Islamic League in London. Other than being involved in various humanitarian projects, he frequently responds to... Answered 3 years ago

It is allowed but Makrouh (Disliked) as we have a Hadeeth from Imam Mohammad Al-Baqir (AS) stating that it is Makrouh to have sexual intercourse between Fajr and sunrise.

Wasa'il Al-Shia by Al-Hurr Al-Aamili, Vol 20, Page 125.

عن عبد الرحمن بن سالم، عن أبيه، عن أبي جعفر (عليه السلام) قال: قلت له: هل يكره الجماع في وقت من الأوقات وإن كان حلالا؟ قال:
نعم ما بين طلوع الفجر إلى طلوع الشمس، ومن مغيب الشمس إلى مغيب الشفق، وفى اليوم الذي تنكسف فيه    الشمس، وفى الليلة التي ينكسف فيها


The Hadeeths explain that it is recommended to be awake between Fajr and sunrise, by being busy in worshiping Allah. Sexual relationship with spouse is recommended in general but there are certain times and situations where it becomes Makrouh.