Note: The mail service will be listening for your connection on TCP port 25. But this information will not be important until you see some Perl code later in the chapter. The message that you prepare can only use alphanumeric characters. If you need to send binary information (like files), use the MIME protocol.
With my first set of twins we were able to tell at 16 weeks and with my second set at 14 weeks. It all just depends on their position. I was having ultrasounds every two weeks so there were alot of oppurtunities to look. It would not matter if they are different sizes. Helpful (8) Nice.
By 18 weeks, an ultrasound technician should be able to identify the sex if the baby is in a position that allows the genitals to be seen. If not, you may be able to find out the sex if you have another ultrasound later. Some people find out their baby's sex through noninvasive prenatal testing (NIPT). This is a blood test that can detect Down syndrome and a few other chromosomal conditions at 10 weeks of pregnancy or later.