Objective: To determine the factors affecting the height of fundus and estimation of gestational age and low birth weight during antenatal period. Material and methods: This descriptive and observational study was conducted at Outpatient department of the Bilawal Medical College with the collaboration of private sector (Hajiani) Hospital in Hyderabad from December 2018 to May 2019. All pregnant women attending the antenatal OPD were included. After taking verbal informed consent and detailed history information gathered, regarding demographic. Patients were assessed examined for symphysio fundal height and ultrasound done to confirm the findings, All the data were recorded in pre-designed proforma and data was analyzed using SPSS version 21. Results: Total 140 females were studied and most of the cases 65.7% were 21-30 years old. 23.6% females were primipara, 74.3% were multipara and only 2.1% were grand multipara. There was a significant positive correlation between gestational age and symphysis-fundal height r-0.883. There were several causes of discrepancy like low birth weight (LBW)16.4%, intrauterine growth retardation (IUGR)14.2% twin pregnancy 12.9%, Polyhydroamnios7.9% Oligohydramnios 7.1% cases & 2.9% were cases of Engagement of head at term. Conclusion: The use of symphysio-fundal height measurement is helpful to gage the correct gestational age in most of the cases, which corresponded well with gestational age confirmed using other techniques like ultrasound. It can be relied upon to give a preliminary cursor of discrepancy in the gestational age in low resource settings. Although low birth weight (LBW), intrauterine growth retardation, twin pregnancy, polyhydramnios, oligohydramnios and engagement of head at term were observed to the causes of discrepancy and factors affecting the height of fundus. Keywords: Symphyso-fundal height (SFH), gestational age, Intrauterine growth retardation (IUGR).