library_construction_protocol: MII oocytes, zygotes and 2-cell embryo blastomeres were dispensed into 12.5 µL CDS sorting solution from the Takara Smart-SeqHT kit (TakaraBio, #634439) and stored at -80 °C. Sequencing libraries were prepared using the Takara Smart-SeqHT Kit (Takara Bio, #634439) according to the manufacturer's instructions. Briefly, cells were lysed and polyadenylated RNA captured in a total volume of 12.5 µL. One-Step first strand synthesis and double stranded cDNA amplification were carried out with 18 PCR cycles. Amplified cDNA was purified via a SPRISelect (Beckman Coulter, #B23317) 1X bead clean-up and eluted in 15 µL Elution Buffer. Nextera Dual Index libraries were prepared with the Nextera XT kit (Illumina, #FC-131-1096). Purified cDNA was normalised to 0.2 ng/µL input and tagmentation was carried out by adding 2.5 µL Tagment DNA Buffer + 1.25 µL Amplicon Tagment mix to 1.25 µL cDNA. The tagmentation reaction was run for 10 min at 55 oC. A final index PCR was performed after adding 2.5 µL Nextera compatible dual indices (at 10 µM) + 3.75 µL NPM PCR Mix. Amplified libraries were purified via a SPRIselect (Beckman Coulter, #B23317) 0.9X bead clean-up. The quality and fragment size distributions of the purified libraries was assessed by a 4200 TapeStation Instrument (Agilent).